Best Macaroni & Cheese.

Ruth Reichl had delcared this to be the world's BEST Macaroni & Cheese.....

Macaroni and Cheese

Topping:
¼ stick (two tablespoons) unsalted butter, melted
2 cups panko (Japanese bread crumbs)
1 cup coarsely grated extra-sharp Cheddar (about 4 ounces)

Mac & Cheese:
3 tablespoons unsalted butter
3 tablespoons all-purpose flour
½ teaspoon red pepper flakes
2 ¾ cups whole milk
¾ cups heavy cream
4 cups coarsely grated extra-sharp Cheddar (about 1 pound)
2 teaspoons Dijon mustard
1 ½ teaspoons salt
¼ teaspoon freshly ground black pepper
¾ pound elbow macaroni

Preheat oven to 400 degrees. Butter a 3-quart shallow baking dish.
Stir together butter, panko, and cheese in a bowl until well combined.
Melt butter in a 5-quart heavy pot over moderately low heat. Whisk in flour and red pepper flakes and cook, whisking, for 3 minutes to make a roux. Whisk in milk in a slow stream, then bring sauce to a boil, whisking constantly. Simmer, whisking occasionally, for 3 minutes. Stir in cream, Cheddar, mustard, salt, and pepper. Remove pot from heat and cover surface of sauce with wax paper to prevent a skin from forming.
Cook macaroni in a 6-quart pot of boiling salted water (1 tablespoon salt per every 4 quarts of water) until al dente. Reserve 1 cup pasta cooking water and drain macaroni.
Stir together macaroni, reserved cooking water, and sauce in a large bowl, then transfer to baking dish (mixture will be loose).
Sprinkle topping evenly over macaroni. Bake until top is golden and bubbling, 25 to 35 minutes.