
Let the mac and cheese sit for 5 minutes for the sauce set and cool slightly. Turn the broiler on high and broil the mac and cheese until the cheese begins to brown all over, about 5 minutes.

Bake the mac and cheese until the cheese is melted and beginning to bubble around the edges, about 20 minutes.In a medium bowl, combine the remaining 2 ounces of cheddar cheese, the mozzarella cheese, and Parmesan cheese.Pour the pasta and sauce into an 8-inch square baking dish with 2-inch-high sides (at this point, the pasta can be wrapped and refrigerated for up to 3 days). Add the cooked pasta to the pot and gently fold to coat with the sauce, then season with 1 teaspoon salt.

In a large pot of boiling salted water, cook macaroni according to package instructions until just.
