diff --git a/.github/actions/prepare-e2e-test/action.yml b/.github/actions/prepare-e2e-test/action.yml
new file mode 100644
index 000000000000..3f5b37b41506
--- /dev/null
+++ b/.github/actions/prepare-e2e-test/action.yml
@@ -0,0 +1,110 @@
+name: 'Prepare E2E test application'
+description:
+  'Sets up the runtimes for an E2E test application, restores the built tarballs and copies the application to
+  `runner.temp/test-application` with pnpm overrides pointing at the tarballs.'
+inputs:
+  test-application:
+    description: 'The name of the test application in dev-packages/e2e-tests/test-applications.'
+    required: true
+  runtime:
+    description: 'The `runtime` of a runtime variant, see dev-packages/e2e-tests/README.md.'
+    default: ''
+  deno-version:
+    description: 'The Deno version to install, if the application needs Deno.'
+    default: 'v2.8.3'
+  artifacts-run-id:
+    description: 'The workflow run that uploaded the tarball artifacts. Defaults to the current run.'
+    default: ''
+  github-token:
+    description: 'Token to download artifacts from `artifacts-run-id`. Only needed when that is set.'
+    default: ''
+
+runs:
+  using: 'composite'
+  steps:
+    - name: Set up Node
+      uses: actions/setup-node@v7
+      with:
+        node-version-file: 'dev-packages/e2e-tests/test-applications/${{ inputs.test-application }}/package.json'
+    - name: Set up Bun
+      if:
+        inputs.test-application == 'node-exports-test-app' || contains(inputs.test-application, 'bun') || inputs.runtime
+        == 'bun'
+      uses: oven-sh/setup-bun@v2
+      with:
+        bun-version: '1.3.14'
+    - name: Set up AWS SAM
+      if: contains(inputs.test-application, 'aws-serverless')
+      uses: aws-actions/setup-sam@v3
+      with:
+        use-installer: true
+        token: ${{ github.token }}
+    - name: Set up Deno
+      if: contains(inputs.test-application, 'deno') || inputs.runtime == 'deno'
+      uses: denoland/setup-deno@v2.0.5
+      with:
+        deno-version: ${{ inputs.deno-version || 'v2.8.3' }}
+    # Keeps the pnpm store on the cache volume for the `pnpm install` of the test application
+    - name: Mount pnpm store
+      uses: ./.github/actions/mount-pnpm-store
+    - name: Install pnpm
+      uses: ./.github/actions/install-pnpm
+
+    # upload-artifact strips the path through the first `*`, so the tarballs are stored as <pkg>/*.tgz and have to be
+    # downloaded into packages/.
+    - name: Restore tarball artifacts
+      uses: actions/download-artifact@v8
+      with:
+        name: build-tarball-output
+        path: ${{ github.workspace }}/packages
+        run-id: ${{ inputs.artifacts-run-id || github.run_id }}
+        github-token: ${{ inputs.github-token }}
+
+    - name: Restore test-utils tarball artifact
+      uses: actions/download-artifact@v8
+      with:
+        name: build-test-utils-tarball-output
+        path: dev-packages/test-utils
+        run-id: ${{ inputs.artifacts-run-id || github.run_id }}
+        github-token: ${{ inputs.github-token }}
+
+    - name: Restore build layer artifacts
+      if: contains(inputs.test-application, 'aws-serverless')
+      uses: actions/download-artifact@v8
+      with:
+        name: build-layer-output
+        path: ${{ github.workspace }}/packages/aws-serverless/build/aws/dist-serverless
+        run-id: ${{ inputs.artifacts-run-id || github.run_id }}
+        github-token: ${{ inputs.github-token }}
+
+    # The Lambda functions install the built workspace packages directly (see `src/stack.ts`).
+    - name: Restore build artifacts
+      if: inputs.test-application == 'aws-serverless'
+      uses: actions/download-artifact@v8
+      with:
+        name: build-output
+        run-id: ${{ inputs.artifacts-run-id || github.run_id }}
+        github-token: ${{ inputs.github-token }}
+
+    - name: Prepare E2E tests
+      run: pnpm run test:prepare
+      shell: bash
+      working-directory: dev-packages/e2e-tests
+
+    - name: Validate E2E test setup
+      run: pnpm run test:validate
+      shell: bash
+      working-directory: dev-packages/e2e-tests
+
+    - name: Copy to temp
+      run:
+        pnpm run ci:copy-to-temp ./test-applications/${{ inputs.test-application }} ${{ runner.temp }}/test-application
+      shell: bash
+      working-directory: dev-packages/e2e-tests
+
+    - name: Add pnpm overrides
+      run:
+        pnpm run ci:pnpm-overrides ${{ runner.temp }}/test-application ${{ github.workspace
+        }}/dev-packages/e2e-tests/packed
+      shell: bash
+      working-directory: dev-packages/e2e-tests
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index f0287b585316..343eccc16d35 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1108,79 +1108,12 @@ jobs:
         uses: actions/checkout@v7
         with:
           ref: ${{ env.HEAD_COMMIT }}
-      - name: Set up Node
-        uses: actions/setup-node@v7
-        with:
-          node-version-file: 'dev-packages/e2e-tests/test-applications/${{ matrix.test-application }}/package.json'
-      - name: Set up Bun
-        if:
-          matrix.test-application == 'node-exports-test-app' || contains(matrix.test-application, 'bun') ||
-          matrix.runtime == 'bun'
-        uses: oven-sh/setup-bun@v2
-        with:
-          bun-version: '1.3.14'
-      - name: Set up AWS SAM
-        if: matrix.test-application == 'aws-serverless' || matrix.test-application == 'aws-serverless-layer'
-        uses: aws-actions/setup-sam@v3
-        with:
-          use-installer: true
-          token: ${{ secrets.GITHUB_TOKEN }}
-      - name: Set up Deno
-        if: contains(matrix.test-application, 'deno') || matrix.runtime == 'deno'
-        uses: denoland/setup-deno@v2.0.5
-        with:
-          deno-version: ${{ matrix.deno-version || 'v2.8.3' }}
-      # Keeps the pnpm store on the cache volume for the `pnpm install` of the test application
-      - name: Mount pnpm store
-        uses: ./.github/actions/mount-pnpm-store
-      - name: Install pnpm
-        uses: ./.github/actions/install-pnpm
-
-      - name: Restore tarball artifacts
-        uses: actions/download-artifact@v8
-        with:
-          name: build-tarball-output
-          path: ${{ env.TARBALL_ARTIFACT_DOWNLOAD_PATH }}
-
-      - name: Restore test-utils tarball artifact
-        uses: actions/download-artifact@v8
+      - name: Prepare E2E test application
+        uses: ./.github/actions/prepare-e2e-test
         with:
-          name: build-test-utils-tarball-output
-          path: dev-packages/test-utils
-
-      - name: Restore build layer artifacts
-        uses: actions/download-artifact@v8
-        if: matrix.test-application == 'aws-serverless' || matrix.test-application == 'aws-serverless-layer'
-        with:
-          name: build-layer-output
-          path: ${{ env.BUILD_LAYER_PATH }}
-
-      # The Lambda functions install the built workspace packages directly (see `src/stack.ts`).
-      - name: Restore build artifacts
-        uses: actions/download-artifact@v8
-        if: matrix.test-application == 'aws-serverless'
-        with:
-          name: build-output
-
-      - name: Prepare e2e tests
-        run: pnpm run test:prepare
-        working-directory: dev-packages/e2e-tests
-
-      - name: Validate e2e tests setup
-        run: pnpm run test:validate
-        working-directory: dev-packages/e2e-tests
-
-      - name: Copy to temp
-        run:
-          pnpm run ci:copy-to-temp ./test-applications/${{ matrix.test-application }} ${{ runner.temp
-          }}/test-application
-        working-directory: dev-packages/e2e-tests
-
-      - name: Add pnpm overrides
-        run:
-          pnpm run ci:pnpm-overrides ${{ runner.temp }}/test-application ${{ github.workspace
-          }}/dev-packages/e2e-tests/packed
-        working-directory: dev-packages/e2e-tests
+          test-application: ${{ matrix.test-application }}
+          runtime: ${{ matrix.runtime }}
+          deno-version: ${{ matrix.deno-version }}
 
       # Installs Playwright while the app builds. Keep it right before the build: the runner sets up a background
       # composite action's steps from the job's shared `github` context, which fails with "Collection was modified" if
diff --git a/.github/workflows/optional-e2e.yml b/.github/workflows/optional-e2e.yml
index b0c52a21961e..8374ea398ec0 100644
--- a/.github/workflows/optional-e2e.yml
+++ b/.github/workflows/optional-e2e.yml
@@ -35,7 +35,6 @@ env:
   HEAD_COMMIT: ${{ inputs.commit }}
 
   # See build.yml
-  TARBALL_ARTIFACT_DOWNLOAD_PATH: ${{ github.workspace }}/packages
   DISABLE_V8_COMPILE_CACHE: '1'
 
 jobs:
@@ -85,64 +84,15 @@ jobs:
         uses: actions/checkout@v7
         with:
           ref: ${{ env.HEAD_COMMIT }}
-      - name: Set up Node
-        uses: actions/setup-node@v7
+      - name: Prepare E2E test application
+        uses: ./.github/actions/prepare-e2e-test
         with:
-          node-version-file: 'dev-packages/e2e-tests/test-applications/${{ matrix.test-application }}/package.json'
-      - name: Set up Bun
-        if:
-          matrix.test-application == 'node-exports-test-app' || contains(matrix.test-application, 'bun') ||
-          matrix.runtime == 'bun'
-        uses: oven-sh/setup-bun@v2
-        with:
-          bun-version: '1.3.14'
-      - name: Set up Deno
-        if: contains(matrix.test-application, 'deno') || matrix.runtime == 'deno'
-        uses: denoland/setup-deno@v2.0.5
-        with:
-          deno-version: ${{ matrix.deno-version || 'v2.8.3' }}
-      # Keeps the pnpm store on the cache volume for the `pnpm install` of the test application
-      - name: Mount pnpm store
-        uses: ./.github/actions/mount-pnpm-store
-      - name: Install pnpm
-        uses: ./.github/actions/install-pnpm
-
-      - name: Restore tarball artifacts
-        uses: actions/download-artifact@v8
-        with:
-          name: build-tarball-output
-          path: ${{ env.TARBALL_ARTIFACT_DOWNLOAD_PATH }}
-          run-id: ${{ inputs.build_run_id }}
+          test-application: ${{ matrix.test-application }}
+          runtime: ${{ matrix.runtime }}
+          deno-version: ${{ matrix.deno-version }}
+          artifacts-run-id: ${{ inputs.build_run_id }}
           github-token: ${{ github.token }}
 
-      - name: Restore test-utils tarball artifact
-        uses: actions/download-artifact@v8
-        with:
-          name: build-test-utils-tarball-output
-          path: dev-packages/test-utils
-          run-id: ${{ inputs.build_run_id }}
-          github-token: ${{ github.token }}
-
-      - name: Prepare E2E tests
-        run: pnpm run test:prepare
-        working-directory: dev-packages/e2e-tests
-
-      - name: Validate test setup
-        run: pnpm run test:validate
-        working-directory: dev-packages/e2e-tests
-
-      - name: Copy to temp
-        run:
-          pnpm run ci:copy-to-temp ./test-applications/${{ matrix.test-application }} ${{ runner.temp
-          }}/test-application
-        working-directory: dev-packages/e2e-tests
-
-      - name: Add pnpm overrides
-        run:
-          pnpm run ci:pnpm-overrides ${{ runner.temp }}/test-application ${{ github.workspace
-          }}/dev-packages/e2e-tests/packed
-        working-directory: dev-packages/e2e-tests
-
       # Installs Playwright while the app builds. Keep it right before the build: the runner sets up a background
       # composite action's steps from the job's shared `github` context, which fails with "Collection was modified" if
       # a foreground step starts at that moment. Starting next to `download-artifact` also made it fail to read the event file.