Preheat your oven to 350°F (175°C) and lightly grease a 9x13-inch baking dish. Boil the macaroni according to the package directions until al dente. Drain and set aside.In a large saucepan, melt half of the butter over medium heat.
Stir in the flour and cook for 1–2 minutes until it’s lightly golden and bubbly.
Gradually whisk in the milk and cream, stirring constantly until the sauce thickens, about 5–7 minutes.
Remove from heat and mix in the cheddar and Gruyère until melted and smooth.
Season with smoked paprika, salt, and pepper.
Stir the cooked macaroni into the cheese sauce.
Pour the mixture into the prepared baking dish.
Melt the remaining butter in a small pan and mix with the panko breadcrumbs.
Combine with Parmesan and sprinkle evenly over the macaroni.
Bake for 20–25 minutes until the top is golden and the sauce is bubbling. For an extra crunchy top, broil 2–3 minutes, watching closely to avoid burning.
Let the casserole rest a few minutes before serving.