1. Preheat your oven to 350°F. Cook the macaroni according to the package instructions until al dente. Drain and set aside.
2. In a large saucepan over medium heat, melt the butter. Stir in the flour and cook for about 1 minute until it forms a paste.
3. Gradually whisk in the milk, ensuring there are no lumps. Continue to cook, stirring constantly, until the mixture thickens, about 5-7 minutes.
4. Remove from heat and stir in the cheddar, mozzarella, and Parmesan cheeses until melted and smooth. Season with salt, pepper, and paprika.
5. Combine the cheese sauce with the cooked macaroni, ensuring every piece is coated.
6. Transfer the mixture to a greased baking dish. In a small bowl, mix the breadcrumbs with the melted butter, then sprinkle evenly over the macaroni.
7. Bake for 25-30 minutes until golden brown and bubbly. Let it cool slightly before serving.

This method of making a roux-based cheese sauce was something I learned from my grandmother, who always emphasized the importance of stirring with love and patience.