- 5 tablespoons butter, plus more for the baking dish
- 1 pound elbow macaroni
- 1/2 cup all-purpose flour
- 6 cups whole milk
- 2 cups grated Gruyere (8 ounces)
- 1 1/2 cups grated Cheddar (6 ounces)
- 1/4 teaspoon cayenne pepper
- Kosher salt
- Heat oven to 400° F. Butter a 9-by-13-inch baking dish or some other shallow 3-quart baking dish.
- Cook the pasta according to the package directions.
- Wipe out the past pot and melt the butter over medium heat. Add the flour and cook, stirring constantly, for 2 minutes (do not let it darken). Still stirring, slowly add the milk. Cook, stirring occasionally, until the sauce slightly thickens, 6 to 8 minutes.
- Add the Gruyère, Cheddar, cayenne, and 1½ teaspoon salt and cook just until the cheeses melt. Mix in the pasta. Transfer the pasta mixture to the prepared baking dish and bake until golden, 25 to 30 minutes.