Preheat oven to 350°F. Spray a 9x13-inch baking dish with nonstick spray.
Bring a large pot of salted water up to a boil. Boil the noodles until they are just shy of al dente, then drain and set aside. It will continue to cook after it is drained and again when it’s mixed with the sauce.
16 ounces dry elbow pasta*
In a medium pot, melt the butter over medium heat. Whisk in the flour and cook over medium-low heat for 5 minutes while whisking constantly.
4 tablespoons salted butter, ¼ cup all-purpose flour
Slowly whisk in the milk, salt, and pepper. Cook until the sauce has thickened, about 4-5 minutes. Stir often, and lower the temperature as needed so the dish doesn't burn.
2½ cups milk, 1 teaspoon kosher salt, 1 teaspoon ground black pepper
Gradually add in cheeses so they melt evenly and don't curdle. Stir in 1 cup yellow cheddar, 1 cup white cheddar cheese, and all of the American cheese, Parmesan cheese, and Romano cheese to the sauce slowly. Cook until all of the cheese is melted.
1½ cups freshly grated yellow cheddar cheese**, 1½ cups freshly grated white cheddar cheese, 8 slices American cheese, ½ cup freshly grated Parmesan cheese, ½ cup freshly grated Romano cheese
Gently fold in the noodles and transfer the mixture to the prepared baking dish.
Top with the remaining yellow and white cheddar.
Bake for 15-20 minutes, or until bubbly.