Instructions

1. Put on a quart or so of water to boil for the noodles. Salt it well, cover, and place on high heat. Set oven to preheat to 375ºF and grease a 1 1/2 or 2 quart baking dish.
2. Make a roux in a deep skillet by melting butter, then whisking in flour until a smooth paste forms. Add mustard, salt and pepper, and cook over medium-low heat for about 60 seconds until you start to smell the flour toasting.
3. Whisk in half the milk and continue whisking until smooth. Add remaining milk and combine. Continue stirring, making sure to get the corners of the pot, until mixture comes to a simmer. Remove from heat and stir in cheeses, reserving 1/4 cup Cheddar for topping. Set aside.
4. By now the water should be boiling. Add the noodles and boil for only 3-4 minutes until beginning to soften. Drain and add the noodles to the cheese sauce.
5. Once coated, spread into your greased pan. (*STOP here if making ahead. Cool. Cover and refrigerate. Add crumbs before baking.)
6. Sprinkle top with bread crumbs and reserved 1/4 cup Cheddar
7. Bake 20-25 minutes or until bubbling and golden brown. (Bake 30-40 minutes if starting with a refrigerated casserole)