- 1 1/2 cups Béchamel sauce
- 1/2 cup grated Gruyère cheese
- 1/4 cup grated Parmesan cheese
- 1 cup cooked puréed onion
- To Béchamel sauce add Gruyère cheese, Parmesan cheese, and onion. Add salt and pepper to taste. Heat until flavors are thoroughly blended and the sauce is smooth.