Preheat the oven to 350°F (175°C) and grease a 9×13-inch baking dish.
Cook the macaroni until al dente, then drain and set aside.
Make the cheese sauce by melting 4 tablespoons of butter in a saucepan, whisking in flour, then slowly adding milk and whipping cream. Cook until thickened.
Stir in seasonings (smoked paprika, salt, and pepper), then remove from heat and mix in the sharp cheddar and Gruyère until smooth.
Combine the pasta and sauce, then transfer to the prepared baking dish.
Prepare the topping by mixing melted butter with panko breadcrumbs, then combining with Parmesan. Sprinkle over the mac and cheese.
Bake for 20-25 minutes, until golden and bubbling. For extra crispiness, broil for 2-3 minutes at the end.