Peel and chop the onion and garlic, sauté in the oil. Clean and chop mushrooms, add mince, fry. Add tomatoes, cook for 10 minutes. Season with salt, pepper and broth.
Sweat the flour in butter, deglaze with milk, season with salt, pepper and nutmeg, simmer for 15 minutes while stirring.
Preheat the oven to 200 degrees (convection 180 degrees).
Layer the minced meat, pasta, and bechamel sauce alternately in a baking dish.