diff --git a/frontend/src/__mocks__/mockDashboardConfig.ts b/frontend/src/__mocks__/mockDashboardConfig.ts
index ef2831e497..370e500251 100644
--- a/frontend/src/__mocks__/mockDashboardConfig.ts
+++ b/frontend/src/__mocks__/mockDashboardConfig.ts
@@ -1,4 +1,5 @@
 import { DashboardConfigKind, KnownLabels } from '~/k8sTypes';
+import { NotebookSize } from '~/types';
 
 type MockDashboardConfigType = {
   disableInfo?: boolean;
@@ -26,6 +27,7 @@ type MockDashboardConfigType = {
   disableDistributedWorkloads?: boolean;
   disableModelRegistry?: boolean;
   disableNotebookController?: boolean;
+  notebookSizes?: NotebookSize[];
 };
 
 export const mockDashboardConfig = ({
@@ -54,6 +56,73 @@ export const mockDashboardConfig = ({
   disableDistributedWorkloads = false,
   disableModelRegistry = true,
   disableNotebookController = false,
+  notebookSizes = [
+    {
+      name: 'XSmall',
+      resources: {
+        limits: {
+          cpu: '0.5',
+          memory: '500Mi',
+        },
+        requests: {
+          cpu: '0.1',
+          memory: '100Mi',
+        },
+      },
+    },
+    {
+      name: 'Small',
+      resources: {
+        limits: {
+          cpu: '2',
+          memory: '8Gi',
+        },
+        requests: {
+          cpu: '1',
+          memory: '8Gi',
+        },
+      },
+    },
+    {
+      name: 'Medium',
+      resources: {
+        limits: {
+          cpu: '6',
+          memory: '24Gi',
+        },
+        requests: {
+          cpu: '3',
+          memory: '24Gi',
+        },
+      },
+    },
+    {
+      name: 'Large',
+      resources: {
+        limits: {
+          cpu: '14',
+          memory: '56Gi',
+        },
+        requests: {
+          cpu: '7',
+          memory: '56Gi',
+        },
+      },
+    },
+    {
+      name: 'X Large',
+      resources: {
+        limits: {
+          cpu: '30',
+          memory: '120Gi',
+        },
+        requests: {
+          cpu: '15',
+          memory: '120Gi',
+        },
+      },
+    },
+  ],
 }: MockDashboardConfigType): DashboardConfigKind => ({
   apiVersion: 'opendatahub.io/v1alpha',
   kind: 'OdhDashboardConfig',
@@ -147,73 +216,7 @@ export const mockDashboardConfig = ({
         },
       },
     ],
-    notebookSizes: [
-      {
-        name: 'XSmall',
-        resources: {
-          limits: {
-            cpu: '0.5',
-            memory: '500Mi',
-          },
-          requests: {
-            cpu: '0.1',
-            memory: '100Mi',
-          },
-        },
-      },
-      {
-        name: 'Small',
-        resources: {
-          limits: {
-            cpu: '2',
-            memory: '8Gi',
-          },
-          requests: {
-            cpu: '1',
-            memory: '8Gi',
-          },
-        },
-      },
-      {
-        name: 'Medium',
-        resources: {
-          limits: {
-            cpu: '6',
-            memory: '24Gi',
-          },
-          requests: {
-            cpu: '3',
-            memory: '24Gi',
-          },
-        },
-      },
-      {
-        name: 'Large',
-        resources: {
-          limits: {
-            cpu: '14',
-            memory: '56Gi',
-          },
-          requests: {
-            cpu: '7',
-            memory: '56Gi',
-          },
-        },
-      },
-      {
-        name: 'X Large',
-        resources: {
-          limits: {
-            cpu: '30',
-            memory: '120Gi',
-          },
-          requests: {
-            cpu: '15',
-            memory: '120Gi',
-          },
-        },
-      },
-    ],
+    notebookSizes,
     templateOrder: ['test-model'],
     templateDisablement: ['test-model'],
   },
diff --git a/frontend/src/__tests__/cypress/cypress/pages/workbench.ts b/frontend/src/__tests__/cypress/cypress/pages/workbench.ts
index d0279617a7..01cbc949f4 100644
--- a/frontend/src/__tests__/cypress/cypress/pages/workbench.ts
+++ b/frontend/src/__tests__/cypress/cypress/pages/workbench.ts
@@ -299,6 +299,11 @@ class CreateSpawnerPage {
   findBucketInput() {
     return cy.findByTestId('field AWS_S3_BUCKET');
   }
+
+  shouldNotHaveCustomContainerSizeInput() {
+    cy.findByTestId('container-size-group').contains('Custom').should('not.exist');
+    return this;
+  }
 }
 
 class EditSpawnerPage extends CreateSpawnerPage {
diff --git a/frontend/src/__tests__/cypress/cypress/tests/mocked/projects/workbench.cy.ts b/frontend/src/__tests__/cypress/cypress/tests/mocked/projects/workbench.cy.ts
index f43db7f18c..47233766a1 100644
--- a/frontend/src/__tests__/cypress/cypress/tests/mocked/projects/workbench.cy.ts
+++ b/frontend/src/__tests__/cypress/cypress/tests/mocked/projects/workbench.cy.ts
@@ -1,4 +1,5 @@
 import {
+  mockDashboardConfig,
   mockDscStatus,
   mockK8sResourceList,
   mockNotebookK8sResource,
@@ -399,10 +400,72 @@ describe('Workbench page', () => {
     });
 
     cy.get('@editWorkbench.all').then((interceptions) => {
-      expect(interceptions).to.have.length(2); // 1 dry run request and 1 actaul request
+      expect(interceptions).to.have.length(2); // 1 dry run request and 1 actual request
     });
   });
 
+  it('Handle deleted notebook sizes in workbenches table', () => {
+    initIntercepts({});
+    cy.interceptOdh(
+      'GET /api/config',
+      mockDashboardConfig({
+        notebookSizes: [
+          {
+            name: 'Medium',
+            resources: {
+              limits: {
+                cpu: '6',
+                memory: '24Gi',
+              },
+              requests: {
+                cpu: '3',
+                memory: '24Gi',
+              },
+            },
+          },
+          {
+            name: 'Large',
+            resources: {
+              limits: {
+                cpu: '14',
+                memory: '56Gi',
+              },
+              requests: {
+                cpu: '7',
+                memory: '56Gi',
+              },
+            },
+          },
+          {
+            name: 'X Large',
+            resources: {
+              limits: {
+                cpu: '30',
+                memory: '120Gi',
+              },
+              requests: {
+                cpu: '15',
+                memory: '120Gi',
+              },
+            },
+          },
+        ],
+      }),
+    );
+    workbenchPage.visit('test-project');
+    const notebookRow = workbenchPage.getNotebookRow('Test Notebook');
+    notebookRow.shouldHaveNotebookImageName('Test Image');
+    notebookRow.shouldHaveContainerSize('Custom');
+    notebookRow.findKebabAction('Edit workbench').click();
+    editSpawnerPage.shouldHaveContainerSizeInput('Custom');
+    workbenchPage.visit('test-project');
+    workbenchPage.findCreateButton().click();
+    createSpawnerPage.findSubmitButton().should('be.disabled');
+    verifyRelativeURL('/projects/test-project/spawner');
+    // Custom container size dropdown option should not be present for create workbench
+    createSpawnerPage.shouldNotHaveCustomContainerSizeInput();
+  });
+
   it('Validate that updating invalid workbench will navigate to the new page with an error message', () => {
     initIntercepts({});
     notFoundSpawnerPage.visit('updated-notebook');
diff --git a/frontend/src/pages/projects/screens/detail/notebooks/NotebookList.tsx b/frontend/src/pages/projects/screens/detail/notebooks/NotebookList.tsx
index a75a88a6d4..09a488652c 100644
--- a/frontend/src/pages/projects/screens/detail/notebooks/NotebookList.tsx
+++ b/frontend/src/pages/projects/screens/detail/notebooks/NotebookList.tsx
@@ -52,6 +52,7 @@ const NotebookList: React.FC = () => {
         <Button
           key={`action-${ProjectSectionID.WORKBENCHES}`}
           onClick={() => navigate(`/projects/${projectName}/spawner`)}
+          data-testid="create-workbench-button"
           variant="primary"
         >
           Create workbench
diff --git a/frontend/src/pages/projects/screens/detail/notebooks/NotebookTableRow.tsx b/frontend/src/pages/projects/screens/detail/notebooks/NotebookTableRow.tsx
index 69b60601f3..4a47cacbe4 100644
--- a/frontend/src/pages/projects/screens/detail/notebooks/NotebookTableRow.tsx
+++ b/frontend/src/pages/projects/screens/detail/notebooks/NotebookTableRow.tsx
@@ -1,17 +1,8 @@
 import * as React from 'react';
 import { ActionsColumn, ExpandableRowContent, Tbody, Td, Tr } from '@patternfly/react-table';
-import {
-  Button,
-  Flex,
-  FlexItem,
-  Icon,
-  Popover,
-  Split,
-  SplitItem,
-  Tooltip,
-} from '@patternfly/react-core';
+import { Button, Flex, FlexItem, Icon, Popover, Split, SplitItem } from '@patternfly/react-core';
 import { useNavigate } from 'react-router-dom';
-import { ExclamationCircleIcon, InfoCircleIcon } from '@patternfly/react-icons';
+import { InfoCircleIcon } from '@patternfly/react-icons';
 import { NotebookState } from '~/pages/projects/notebook/types';
 import NotebookRouteLink from '~/pages/projects/notebook/NotebookRouteLink';
 import NotebookStatusToggle from '~/pages/projects/notebook/NotebookStatusToggle';
@@ -22,6 +13,7 @@ import { TableRowTitleDescription } from '~/components/table';
 import { ProjectObjectType, typedObjectImage } from '~/concepts/design/utils';
 import DashboardPopupIconButton from '~/concepts/dashboard/DashboardPopupIconButton';
 import { getDescriptionFromK8sResource, getDisplayNameFromK8sResource } from '~/concepts/k8s/utils';
+import { NotebookSize } from '~/types';
 import useNotebookDeploymentSize from './useNotebookDeploymentSize';
 import useNotebookImage from './useNotebookImage';
 import NotebookSizeDetails from './NotebookSizeDetails';
@@ -51,7 +43,14 @@ const NotebookTableRow: React.FC<NotebookTableRowProps> = ({
   const { currentProject } = React.useContext(ProjectDetailsContext);
   const navigate = useNavigate();
   const [isExpanded, setExpanded] = React.useState(false);
-  const { size: notebookSize, error: sizeError } = useNotebookDeploymentSize(obj.notebook);
+  const { size: notebookSize } = useNotebookDeploymentSize(obj.notebook);
+  const lastDeployedSize: NotebookSize = {
+    name: 'Custom',
+    resources: obj.notebook.spec.template.spec.containers[0].resources ?? {
+      limits: {},
+      requests: {},
+    },
+  };
   const [notebookImage, loaded, loadError] = useNotebookImage(obj.notebook);
 
   return (
@@ -124,7 +123,7 @@ const NotebookTableRow: React.FC<NotebookTableRowProps> = ({
                   }
                 >
                   <DashboardPopupIconButton
-                    aria-label="Notebook image has out of date Elrya version"
+                    aria-label="Notebook image has out of date Elyra version"
                     data-testid="outdated-elyra-info"
                     icon={
                       <Icon status="info">
@@ -143,14 +142,7 @@ const NotebookTableRow: React.FC<NotebookTableRowProps> = ({
               spaceItems={{ default: 'spaceItemsXs' }}
               alignItems={{ default: 'alignItemsCenter' }}
             >
-              <FlexItem>{notebookSize?.name ?? 'Unknown'}</FlexItem>
-              {sizeError && (
-                <Tooltip content={sizeError}>
-                  <Icon aria-label="error icon" role="button" status="danger" tabIndex={0}>
-                    <ExclamationCircleIcon />
-                  </Icon>
-                </Tooltip>
-              )}
+              <FlexItem>{notebookSize?.name ?? 'Custom'}</FlexItem>
             </Flex>
           </Td>
         ) : null}
@@ -212,7 +204,7 @@ const NotebookTableRow: React.FC<NotebookTableRowProps> = ({
           </Td>
           <Td dataLabel="Limits">
             <ExpandableRowContent>
-              {notebookSize && <NotebookSizeDetails notebookSize={notebookSize} />}
+              <NotebookSizeDetails notebookSize={notebookSize || lastDeployedSize} />
             </ExpandableRowContent>
           </Td>
           <Td />
diff --git a/frontend/src/pages/projects/screens/spawner/SpawnerPage.tsx b/frontend/src/pages/projects/screens/spawner/SpawnerPage.tsx
index d3e090c8f7..20e8f863f5 100644
--- a/frontend/src/pages/projects/screens/spawner/SpawnerPage.tsx
+++ b/frontend/src/pages/projects/screens/spawner/SpawnerPage.tsx
@@ -11,7 +11,7 @@ import {
   StackItem,
 } from '@patternfly/react-core';
 import ApplicationsPage from '~/pages/ApplicationsPage';
-import { ImageStreamAndVersion } from '~/types';
+import { ImageStreamAndVersion, NotebookSize } from '~/types';
 import GenericSidebar from '~/components/GenericSidebar';
 import NameDescriptionField from '~/concepts/k8s/NameDescriptionField';
 import { ProjectDetailsContext } from '~/pages/projects/ProjectDetailsContext';
@@ -61,7 +61,7 @@ const SpawnerPage: React.FC<SpawnerPageProps> = ({ existingNotebook }) => {
     imageStream: undefined,
     imageVersion: undefined,
   });
-  const { selectedSize, setSelectedSize, sizes } = useNotebookSize();
+  const { selectedSize, setSelectedSize, sizes } = useNotebookSize(!!existingNotebook);
   const [supportedAcceleratorProfiles, setSupportedAcceleratorProfiles] = React.useState<
     string[] | undefined
   >();
@@ -97,10 +97,16 @@ const SpawnerPage: React.FC<SpawnerPageProps> = ({ existingNotebook }) => {
 
   const { size: notebookSize } = useNotebookDeploymentSize(existingNotebook);
   React.useEffect(() => {
+    const customSize: NotebookSize = { name: 'Custom', resources: {} };
     if (notebookSize) {
       setSelectedSize(notebookSize.name);
+    } else {
+      if (existingNotebook && !sizes.some((size) => size.name === 'Custom')) {
+        sizes.unshift(customSize);
+      }
+      setSelectedSize(customSize.name);
     }
-  }, [notebookSize, setSelectedSize]);
+  }, [notebookSize, setSelectedSize, sizes, existingNotebook]);
 
   const [notebookAcceleratorProfileState, setNotebookAcceleratorProfileState] =
     useNotebookAcceleratorProfile(existingNotebook);
diff --git a/frontend/src/pages/projects/screens/spawner/deploymentSize/ContainerSizeSelector.tsx b/frontend/src/pages/projects/screens/spawner/deploymentSize/ContainerSizeSelector.tsx
index d717630c35..9acaa361c1 100644
--- a/frontend/src/pages/projects/screens/spawner/deploymentSize/ContainerSizeSelector.tsx
+++ b/frontend/src/pages/projects/screens/spawner/deploymentSize/ContainerSizeSelector.tsx
@@ -35,7 +35,11 @@ const ContainerSizeSelector: React.FC<ContainerSizeSelectorProps> = ({
         {sizes.map((size) => {
           const { name } = size;
           const desc = getSizeDescription(size);
-          return <SelectOption key={name} value={name} description={desc} />;
+          return name === 'Custom' ? (
+            <SelectOption key={name} value={name} />
+          ) : (
+            <SelectOption key={name} value={name} description={desc} />
+          );
         })}
       </Select>
 
diff --git a/frontend/src/pages/projects/screens/spawner/useNotebookSize.ts b/frontend/src/pages/projects/screens/spawner/useNotebookSize.ts
index 62ded00e44..0ca1c1be38 100644
--- a/frontend/src/pages/projects/screens/spawner/useNotebookSize.ts
+++ b/frontend/src/pages/projects/screens/spawner/useNotebookSize.ts
@@ -14,7 +14,9 @@ export const getNotebookSizes = (config: DashboardConfigKind): NotebookSize[] =>
   return sizes;
 };
 
-export const useNotebookSize = (): {
+export const useNotebookSize = (
+  isExistingNotebook: boolean,
+): {
   selectedSize: NotebookSize;
   setSelectedSize: (size: string) => void;
   sizes: NotebookSize[];
@@ -28,15 +30,15 @@ export const useNotebookSize = (): {
   const setSelectedSizeSafe = React.useCallback(
     (name: string) => {
       let foundSize = sizes.find((size) => size.name === name);
-      if (!foundSize) {
+      if (!foundSize && isExistingNotebook) {
         [foundSize] = sizes;
         notification.warning(
           'The size you select is no longer available, we have set the size to the default one.',
         );
       }
-      setSelectedSize(foundSize);
+      setSelectedSize(foundSize ?? sizes[0]);
     },
-    [notification, sizes],
+    [notification, sizes, isExistingNotebook],
   );
 
   return { selectedSize, setSelectedSize: setSelectedSizeSafe, sizes };