Depending on the purpose of your white sauce, you may want to flavor it to make it more interesting. In my Creamed Peas recipe, I sauté some onion and bacon in the butter before stirring in the flour. For a smooth sauce, you'll need to strain off the aromatics - but I never do. You can also turn your Béchamel into a cheese sauce by stirring 1-2 cups grated cheese into the finished, just-cooked and still piping hot sauce. Consider reducing the flour and butter by 1 tablespoon each if planning to add 2 cups of a very melty cheese (such as mozzarella), otherwise the sauce can be too thick/too rich. To make a creamy mushroom sauce, sauté diced onion, minced garlic and chopped mushrooms in the butter before adding the flour.