Season with additional salt and pepper, if desired, and serve warm.
Notes
Butter: I use salted butter in this recipe.
Onion: The onion is optional. If omitting the onion, reduce the butter to 2 tablespoons.
Cheddar cheese: Gouda is a fairly mild cheese. Using mild cheddar will help more of the flavor to come through. If you use sharp cheddar, you won't get as much of the gouda flavor.