In a sauce pan, melt about 3 T butter. When melted, whisk in 3 T flour until smooth and bubbly. Turn down heat. Slowly, slowly, add 2 cups warmed milk, and whisk in.
At this point, you can also add a smidge of roasted or sauted minced garlic and onion.
Once the sauce is thick and creamy, add around a cup of shredded decent cheese. It can be any type -- I've used mozzarella, real parmesan, asiago, swiss, provolone, gouda. A good percentage should be yellow cheese -- cheddar, colby, longhorn, etc.
Add dashes of dry mustard, white pepper, celery salt, white wine, horseradish and Clancy's Fancy Hot Sauce (or another hot sauce). Then add noodles, and mix well.
Turn into a baking dish, and mix again with about a cup of shredded yellow cheese, then top with croutons and bread crumbs.
Bake in a 350 degree oven until it smells really really good.