Cheesy Bacon and Mushroom Baked Macaroni

Last night's dinner was the essence of comfort. I confess, growing up I always enjoyed the blue-box variety of mac & cheese, but this grownup-foodie version is vastly superior in every way imaginable. Even my children thought so, which is not too difficult to imagine because there is something about the aroma of bacon that lets us know... this is gonna be good.

Ingredients:
1/2 lb elbow macaroni
8 slices bacon
1 medium/small onion, diced
1/2 cup chopped mushrooms
2 cups cheese, I used a Mexican taco variety containing cheddar and asadero -- very yum!
2 cups milk
2 tablespoons melted butter
1 egg
2 tablespoons all-purpose flour
black pepper
paprika
salt
crust: 1/2 bread crumbs and 2 tablespoons butter

Preparation:
In a pot of salted boiling water cook macaroni. Meanwhile, preheat oven to 400 degrees; and in a large pan, cook bacon until crisp. Once bacon is cooked, remove from pan and set aside. Saute onions in bacon fat, once they begin to tenderize add mushrooms; cook until tender and brown. In a medium mixing bowl, combine cheese, milk, melted butter, 1 egg, 2 tablespoons flour; stir until well mixed. Once macaroni is cooked drain and toss in pan with bacon fat and sauteed onion and mushrooms. Turn heat to low and pour in cheese mixture. Stir to combine and bring heat back to medium. Stir in bacon. Bring mixture to a boil for a few minutes, stirring moderately. After the sauce has thickened, pour the macaroni into a 2 1/2 quart baking dish. Top with bread crumbs and break up remaining two tablespoons of butter on top. Bake for approximately 25 minutes, or until the crust is browned. Let stand five minutes, then serve.