Clean and thoroughly clean the mushrooms. Turn out the stems and chop them finely. Peel and chop the onion. Wash thyme, pluck off leaves
Fry the onion in hot oil. Add the mushroom stems and fry until the water has evaporated. Remove the pan from the stove. Press sausage meat directly from the skin into the pan. Mix everything with mustard and thyme, except for something to sprinkle. Seasoning
Season the mushrooms and fill with the sausage meat. Place in an ovenproof dish. Grate the cheese coarsely and spread on top. Wash and clean the tomatoes, dice roughly and distribute around the mushrooms. Pour on broth. Bake in the preheated oven (electric cooker: 200 °C / convection oven: 175 °C / gas: level 3) for about 20 minutes. Sprinkle with remaining thyme