Backup your project, possibly using git or some other version control system

Delete the windows/runner/CMakeLists.txt and windows/runner/Runner.rc
files

Run flutter create --platforms=windows .

Review the changes to your windows/runner/CMakeLists.txt and
windows/runner/Runner.rc files

Verify your app builds using flutter build windows

Note:
  Follow the run loop migration guide if the build fails
  with the following error message:

Example

PR 721 shows the migration work for the
Flutter Gallery app.