The Preparation
Preheat oven to 375°F. Cook macaroni until just shy of al dente (it will finish in the oven). Drain.
Make a roux: melt butter in a large pot, whisk in flour, cook 2 minutes.
Slowly whisk in milk and cream. Cook until thickened, about 5 minutes.
Off heat, stir in cheeses, mustard, and onion powder. Season with salt and pepper.
Combine pasta with cheese sauce and pour into a buttered 9x13 baking dish.
Mix panko with melted butter and additional cheddar. Spread evenly over the top.
Bake 25-30 minutes until bubbly and golden on top.
Let rest 5 minutes before serving.
