Wash and clean the cauliflower and divide into florets. Cook in boiling salted water for 5-6 minutes. Drain and rinse. Wash the meat, dab dry and fry in 2 tablespoons of hot oil in a pan for 1 minute on each side.
Peel onion and garlic. Dice onion and press garlic through a garlic press. Fry the onion and garlic in a pan until transparent. Add tomatoes, bring to the boil and season with salt, pepper and herbs.
Stir in the sauce thickener, bring to the boil and set aside. Grease the casserole dish. Cover the bottom with some sauce. Put cauliflower and meat into the dish and pour the rest of the sauce on top. Cook in the preheated oven (electric cooker: 175 °C/ gas: level 2) for about 30 minutes.
Mix the cheese and hazelnuts and add to the casserole 10 minutes before the end of the cooking time. Garnish as desired with fresh herbs.