01 - Preheat oven to 350°F if using the topping. Lightly grease a 2-quart baking dish as needed.
02 - Boil a large pot of salted water. Cook macaroni until al dente according to package directions. Drain and set aside.
03 - In a large saucepan over medium heat, melt butter. Whisk in flour and cook for 1-2 minutes until lightly golden.
04 - Gradually whisk in warm milk and cream. Stir constantly until thickened, about 4-5 minutes.
05 - Reduce heat to low. Stir in cheddar, Gruyère, and mozzarella until fully melted. Add Dijon mustard, garlic powder, onion powder, salt, and black pepper.
06 - Add cooked macaroni to the sauce and gently fold until well coated.
07 - Transfer mixture to prepared baking dish. Combine panko, melted butter, and Parmesan; sprinkle over top. Bake for 15-20 minutes until golden and bubbly.