Basic Creamy Cheese Sauce

2 tablespoons butter
2 tablespoons flour
2 cups whole milk (or cream or half and half, I've never tried it with less than whole milk)
2 cups cheese
salt and pepper to taste

Melt butter in a saucepan over medium heat.  Whisk in flour and continue cooking until mixture is lightly golden.  Whisk in milk and bring to a boil.  Once it starts to thicken turn heat to low and add cheese, salt, and pepper.  Once the cheese is melted it's done!

This is the basic recipe I use whenever I need a creamy cheese sauce.  Minor variations make cheesy potatoes with ham, or pasta alfredo.  You can saute garlic and/or onions in the butter.  You can increase or decrease the cheese to your taste.  You can mix different kinds of cheese.  You can serve as-is over pasta straight from the stovetop, or you can mix it into a casserole and bake.