Cook the Pasta: Preheat your oven to 350°F (175°C). Cook the macaroni according to the package instructions until al dente. Drain and set aside.
Make the Cheese Sauce: In a medium saucepan, melt the butter over medium heat. Stir in the flour and whisk continuously for about 2 minutes until it forms a smooth paste.
Add Milk and Cheese: Gradually whisk in the milk and cook until the mixture thickens and bubbles. Remove from heat and stir in the cheddar cheese, mozzarella cheese, salt, black pepper, mustard powder, and paprika until the cheese is melted and the sauce is smooth.
Combine Pasta and Sauce: In a large mixing bowl, combine the cooked macaroni and cheese sauce. Mix until the pasta is fully coated with the sauce.
Prepare for Baking: Transfer the macaroni and cheese mixture to a greased baking dish. Sprinkle the grated Parmesan cheese and breadcrumbs evenly over the top.
Bake: Bake in the preheated oven for 20-25 minutes, or until the top is golden and bubbly.
Serve: Let the baked macaroni and cheese rest for a few minutes before serving.