Cook the Pasta: In a large pot, bring salted water to a boil. Add the pasta and cook according to the package instructions until al dente. Drain and set aside.
Prepare the Cheese Sauce: In a separate saucepan, melt the 1/2 cup of butter over medium heat. Add the flour and whisk continuously for about 2-3 minutes to make a roux, which will thicken the sauce. Slowly pour in the milk while whisking to avoid lumps. Continue to cook, stirring constantly, until the mixture thickens, about 5-7 minutes.
Add the Cheeses: Reduce the heat to low and add the cheddar, mozzarella, and Parmesan cheeses to the sauce. Stir until the cheese is fully melted and the sauce is smooth and creamy. Season the sauce with salt, black pepper, paprika, and cayenne pepper (if using). Mix well.
Combine Pasta and Cheese Sauce: Add the cooked pasta to the cheese sauce and stir to coat the pasta evenly with the creamy mixture.
Prepare the Topping: In a small skillet, melt 2 tablespoons of butter over medium heat. Add the breadcrumbs and sauté for a few minutes until they turn golden brown.
Bake the Mac and Cheese: Preheat your oven to 350°F (175°C). Transfer the mac and cheese mixture to a greased baking dish. Sprinkle the toasted breadcrumbs evenly over the top.
Baking: Place the baking dish in the preheated oven and bake for about 20-25 minutes, or until the top is golden brown and the mac and cheese is bubbling around the edges.
Garnish and Serve: If desired, garnish with chopped fresh parsley for a pop of color and added flavor. Serve the classic Mac and Cheese hot and enjoy!