Clean and wash the broccoli and cut into small florets. Prepare the pasta according to the package instructions in boiling salted water according to the package instructions. Add the broccoli about 8 minutes before the end of the cooking time. Drain the pasta with broccoli in a colander and drain.
Wash the tomatoes and cut them in half. Peel the onion and chop finely. For the sauce, let the fat melt in a saucepan, sauté the onion cubes in it, dust with flour, sweat and gradually deglaze with the broth and milk.
Bring the sauce to the boil while stirring and stir in 75 g of grated cheese. Season to taste with salt, pepper, sugar and nutmeg. Mix the pasta, broccoli, tomatoes and sauce and place in a large enough ovenproof baking dish. Sprinkle with the rest of the cheese. Bake in a preheated oven at 200 degrees (convection: 175 degrees) for about 30 minutes.