In a large (10 to 12-inch) pan, cook butter and onions over medium-low heat for 12 to 15 minutes, until onions are lightly browned. Heat Defatted turkey drippings plus chicken stock in another pot.
Sprinkle flour into pan, whisk in, then add salt and pepper. Cook for 2 to 3 minutes. Add hot chicken stock mixture and Brandy or Cognac, and cook uncovered for 4 to 5 minutes until thickened. Add wine and cream. Add salt and pepper to your taste.