Sauté the grated onion in a pan for 5 minutes, add the ground beef, and once browned stir in the tomato paste and salt and cook for another 10 minutes.

Boil the tube pasta in salted water for 2 minutes less than the package instructions, then drain.

Melt the butter, whisk in the flour and cook for 2 minutes, slowly pour in the milk while stirring, and cook for 5 minutes until thickened; remove from heat and whisk in the egg.

Layer the pasta, meat sauce and béchamel into small oven bowls, sprinkle with grated kaşar, place in the airfryer basket and cook at 190°C for 20 minutes. If you don't have an airfryer, you can bake the bowls the same way in the oven.