01 -
Preheat oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish.
02 -
Cook the macaroni in salted boiling water until al dente. Drain and set aside.
03 -
In a large saucepan, melt 4 tbsp butter over medium heat. Whisk in the flour and cook for 1–2 minutes to form a roux.
04 -
Gradually whisk in the warm milk and cream, stirring constantly until smooth and thickened (about 5 minutes).
05 -
Stir in the mustard, garlic powder, salt, and pepper. Reduce heat to low.
06 -
Add cheddar, mozzarella, and Parmesan cheeses, stirring until melted and smooth.
07 -
Combine the cheese sauce with the cooked pasta, mixing well to coat.
08 -
Pour the mixture into the prepared baking dish.
09 -
In a small bowl, mix panko, melted butter, and optional Parmesan. Sprinkle evenly over the top.
10 -
Bake uncovered for 20–25 minutes, or until bubbling and golden brown on top.
11 -
Let rest 5–10 minutes before serving.