3/4 pound elbow macaroni
2 tablespoons unsalted butter
2 cups coarse dry bread crumbs
1 cup coarsely grated extra-sharp Cheddar (about 4 ounces)
For cheese sauce
3 tablespoons unsalted butter
3 tablespoons all-purpose flour
1/2 teaspoon dried hot red pepper flakes
2 3/4 cups whole milk
3/4 cups heavy cream
4 cups coarsely grated extra-sharp Cheddar (about 1 pound)
2 teaspoons Dijon mustard
1 1/2 teaspoons salt
1/4 teaspoon freshly ground black pepper
*NOTE to my forgetful self...the milk and cream are added at separate times.*
Preheat oven to 400°F and butter a 3-quart shallow baking dish. Fill a 6-quart kettle three fourths full with salted water and bring to a boil for macaroni.
Make topping: Melt butter and in a bowl stir together with bread crumbs and Cheddar until combined well. Topping may be made 1 day ahead and chilled, covered.
Make sauce: In a 5-quart heavy saucepan melt butter over moderately low heat and stir in flour and red pepper flakes. Cook roux, stirring, 3 minutes and whisk in milk. Bring sauce to a boil, whisking constantly, and simmer, whisking occasionally, 3 minutes. Stir in cream, Cheddar, mustard, salt, and pepper. Remove pan from heat and cover.
Cook macaroni in boiling water until al dente. Reserve 1 cup cooking water and drain macaroni in colander. In a large bowl stir together macaroni, reserved cooking water, and sauce. Transfer mixture to baking dish.
Sprinkle topping evenly over macaroni and bake in middle of oven 20 to 25 minutes, or until golden and bubbling.