01 - In a large pot, combine the pasta and whole milk. Heat over medium, stirring frequently to prevent sticking, and bring to a gentle simmer.
02 - Cook the pasta in the milk, stirring often, until pasta is al dente and most of the milk is absorbed, about 12 to 15 minutes.
03 - Reduce the heat to low. Add unsalted butter, mustard powder, garlic powder, onion powder, salt, and ground black pepper. Stir until butter melts and spices are integrated.
04 - Gradually add grated cheddar, mozzarella, and Parmesan cheeses, stirring constantly until melted and mixture reaches a creamy consistency.
05 - Remove from heat. Adjust seasoning as needed after tasting.
06 - Serve hot, garnished with chopped fresh parsley and a sprinkle of smoked paprika, if desired.