01 -
Preheat oven to 350°F and grease a 9x13-inch baking dish with butter or non-stick spray.
02 -
In a large saucepan, melt unsalted butter over medium heat. Whisk in all-purpose flour and cook for 1 to 2 minutes until mixture turns pale golden, stirring constantly.
03 -
Gradually add whole milk in a slow stream while whisking, then continue stirring over medium heat until sauce thickens, about 5 minutes. Stir in salt, black pepper, and paprika until incorporated.
04 -
Remove saucepan from heat and add 2 cups shredded cheddar, mozzarella, and Parmesan. Stir until cheeses melt and sauce becomes smooth.
05 -
Mix cooked elbow macaroni into the cheese sauce until evenly coated, then transfer mixture to prepared baking dish. Top evenly with remaining 1 cup cheddar and sprinkle panko breadcrumbs over the surface.
06 -
Bake in preheated oven for 30 to 45 minutes or until top is golden and pasta is heated through. Allow to rest 5 minutes before serving.