Heat the oven to 350°F (175°C) and lightly grease a 9x13-inch baking dish.

Bring 4 quarts of water to a rolling boil in a large pot. Add 1 tablespoon salt and cook the elbow pasta according to the package directions until al dente. Drain well without rinsing and set aside.

Melt the salted butter in the same empty pot over medium heat.

Whisk the all-purpose flour into the melted butter. Lower the heat to medium-low and cook for 3 to 5 minutes, whisking continuously.

Gradually whisk in the whole milk. Add 1 teaspoon salt and the pepper, then continue cooking and whisking for 4 to 5 minutes, until the sauce is thick enough to coat the back of a spoon.

Lower the heat to low or take the pot off the heat. Add 1 cup yellow cheddar, 1 cup white cheddar, all of the cubed American cheese, Parmesan, and Romano. Stir gradually until the cheeses melt completely and the sauce is smooth.

Add the cooked elbow pasta to the cheese sauce and fold until the noodles are evenly covered.

Pour the macaroni and cheese into the prepared 9x13-inch baking dish and spread it into an even layer.

Scatter the remaining ½ cup yellow cheddar and ½ cup white cheddar evenly over the surface.

Bake uncovered at 350°F (175°C) for 15 to 20 minutes, until the edges are bubbling and the cheese on top is golden brown.

Remove the dish from the oven and let the mac and cheese stand for 2 to 3 minutes before serving warm.