Sprinkle the reserved cheddar and American cheese evenly over the pasta, then scatter the cracker mixture on top.

Melt the remaining 4 tablespoons butter in a bowl in the microwave stir in the crushed crackers and parmesan.

Brush a 9-by-13-inch baking dish with melted butter.

Stir in the pasta, adding the reserved pasta water as needed to make a creamy sauce. Stir in the havarti and all but 1 cup each of the cheddar and American cheese cook, stirring, until the cheese just melts, about 1 more minute. Whisk in the milk and cook, whisking occasionally, until the sauce begins to boil and thicken, about 5 minutes. Whisk in the flour, mustard powder, Worcestershire sauce, hot sauce and cayenne and cook, whisking, until the mixture is smooth and slightly golden, about 2 minutes.

Meanwhile, melt 4 tablespoons butter in a large saucepan over medium heat.

Reserve 1/2 cup cooking water, then drain the pasta and rinse under cold water. Add the pasta and cook until just slightly softened, about 6 minutes. Bring a large pot of salted water to a boil.

Ritz cracker topping for mac and cheese