Cook the maccheroni in salted boiling water, reducing the cooking time by 3-4 minutes from what’s indicated on the package.
Meanwhile, melt the cheeses into the warmed béchamel sauce.
Once the pasta is cooked, transfer it to an oven-safe dish, pour the béchamel sauce over it, and sprinkle with Parmesan cheese and a few small pieces of butter.
Cook it under the grill of the oven (180°) for 8 to 10 minutePlace the dish under the oven grill at 180°C (350°F) for 8 to 10 minutes, until golden and bubbling.