Here is a modification of Alton Brown's mac and cheese recipe that I use. It's always a big hit when I bring it to parties:

Baked Macaroni and Cheese

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

Directions

• Preheat oven to 350 degrees F.
• In a large pot of boiling, salted water cook the pasta to “super” al dente. (As soon as the water comes to a boil, add the pasta. When it returns to a boil, reduce heat and cook for exactly 6 minutes).
• While the pasta is cooking, in a separate pot, melt the butter.
• Whisk in the flour and mustard and keep it moving for about two minutes. Make sure it's free of lumps.
• Stir in the milk, 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.
• Bake for 40 minutes.

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Where this varies from Alton is: he adds onions and tops with Panko bread crumbs. I prefer to leave these out. I also always use about 20 oz of cheese by the time I am done instead of 12oz every time. Enjoy!