Place butter in a 11x7x1 1/2" baking dish (or similar size). Heat butter, in baking dish, in a 325 degree oven 5 min or until melted, tilting to coat dish; remove from oven. Pour croutons over butter then set aside.
Combine milk, eggs, and mustard; mix well. Sprinkle 1/2 of bacon over croutons, all of the cheese, remaining bacon. Pour egg mixture over the layered base.
Bake at 325 for 40 to 50 minutes or until set. Let stand at room temp for 5-10 min before serving.
Joan's notes
CHRISTMAS STANDARD YOU CAN SUB HAM OR PRECOOKED AND DRAINED SAUSAGE FOR BACON UNSEASONED CROUTONS OR UNSEASONED DRIED BREAD CUBES OR STRIPS.