Bring a large pot of salted water to a boil. Cook the elbow macaroni for 1 minute less than package directions until al dente. Drain well without rinsing.

Melt the unsalted butter in a heavy saucepan over medium heat. Whisk in the flour and cook for 1-2 minutes until it forms a pale golden paste.

Slowly pour in the whole milk and heavy cream, whisking constantly until the mixture thickens slightly and coats the back of a spoon.

Reduce heat to low. Stir in the salt, pepper, and dry mustard. Gradually fold in the sharp cheddar and American cheese until completely melted into a thick, glossy bright yellow-orange sauce.

Fold the plump cooked macaroni noodles into the cheese sauce until heavily coated.

Transfer the mixture to a greased 9x13 rustic ceramic baking dish. Top evenly with the Colby Jack and Parmesan cheese blend. Bake at 375°F (190°C) for 15-20 minutes.

Turn the oven to broil for the final 2-3 minutes. Watch closely until the top features a beautifully baked, slightly charred and bubbly crust with tones of golden brown.