Ingredients
1 pound short pasta, such as elbow macaroni, cavatappi, or rigatoni
Kosher salt and freshly ground pepper
3 tablespoons butter
1/4 cup flour
2 teaspoons mustard powder
3 cups warm whole milk, warmed
1 cup (4 ounces) finely chopped American cheese
2 cups (8 ounces) grated sharp cheddar
1 cup (2 ounces) grated Parmesan
Preparation
Boil pasta in a medium pot of boiling salted water until al dente, about 2 minutes less than per package instructions. Drain, reserving 1 cup pasta water.
Return empty pot to medium heat and add butter. When butter melts and foams, add flour and whisk until darkened slightly, 1 to 2 minutes. Add mustard powder and whisk to combine. Slowly whisk in milk. Bring to a boil, then reduce heat to medium and cook, stirring often, until thick enough to coat the back of a spoon, 3 to 4 minutes.
Reduce heat to low and add cheese in 3 batches, starting with American. Follow with cheddar and Parmesan. Whisk to fully combine after adding each cheese. Season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Add pasta, stir to coat, and serve.
