Baked Mac and Cheese

This is probably the best baked mac and cheese I have ever had.
It is Alton Brown's who is one of my fav on the Food Network.
It calls for Panko bread crumbs, but I used regular, and it was still amazing.
Enjoy.

Ingredients
1/2 pound elbow macaroni
3 tablespoons butter
3 tablespoons flour
1 tablespoon powdered mustard
3 cups milk
1/2 cup onion, diced
1 bay leaf
1/2 teaspoon paprika
1 large egg
12 ounces sharp cheddar, shredded
1 teaspoon kosher salt
black pepper

Topping:
3 tablespoons butter
1 cup bread crumbs

Directions
Preheat oven to 350 degrees .
In a large pot of boiling, salted water cook the pasta to al dente.
While the pasta is cooking, in a separate pot, melt the butter.
Whisk in the flour and mustard and keep it moving for about five minutes.
Make sure it's free of lumps.
Stir in the milk, onion, bay leaf, and paprika.
Simmer for ten minutes and remove the bay leaf.
Temper in the egg. Stir in 3/4 of the cheese. Season with salt and pepper.
Fold the macaroni into the mix and pour into a 2-quart casserole dish.
Top with remaining cheese.
Melt the butter in a saute pan and toss the bread crumbs to coat.
Top the macaroni with the bread crumbs. Bake for 30 minutes.
Remove from oven and rest for five minutes before serving.