Cook the pasta
Bring a large pot of salted water to a boil. Cook the macaroni according to package instructions until al dente. Drain and set aside.
Make the cheese sauce
In a medium saucepan, melt 4 tablespoons of butter over medium heat. Whisk in the flour and cook for 1-2 minutes, stirring constantly, to create a roux.
Gradually whisk in the milk and cream, ensuring no lumps remain. Cook until the mixture thickens, about 5 minutes.
Stir in garlic powder, mustard powder, paprika (if using), and a pinch of salt and pepper. Remove from heat and stir in the cheddar, mozzarella, and Gruyère until melted and smooth.
Combine pasta and sauce
In a large mixing bowl, combine the cooked pasta with the cheese sauce, mixing well to coat every piece of pasta.
Prepare the topping
In a small bowl, mix panko breadcrumbs with 2 tablespoons of melted butter until evenly coated.
Assemble and bake
Preheat the oven to 375°F (190°C). Transfer the mac and cheese mixture to a greased 9x13-inch baking dish. Spread the breadcrumb topping evenly over the pasta.
Bake for 20-25 minutes, or until the top is golden brown and crispy.
Serve and enjoy
Remove from the oven and let cool slightly before serving. Enjoy warm for the ultimate ooey-gooey experience!