Knead the baking mix and 170 ml of lukewarm water with the dough hooks of the mixer at the highest setting for 3-5 minutes to form a smooth dough. Cover and leave to rise for approx. 45 minutes in a warm place until it has grown considerably larger.
In the meantime peel the onions and cut them into slices. Clean the mushrooms, possibly wash and halve them. Peel garlic, chop finely. Clean, wash and chop the spring onions. Heat 2 tablespoons of oil in a large pan. Sauté the mushrooms, fry the garlic and spring onions briefly. Season with salt, pepper and 2 tsp. thyme, remove. Heat 2 tbsp. oil in the frying fat. Fry the onions in it. Sprinkle with sugar and caramelise over low heat for about 10 minutes while stirring. Mix in the mushroom mixture, season to taste again. Let cool down briefly. Grate cheese coarsely, stir in.
Preheat oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer). Pat meat dry. Place 2 roulades in an ovenproof dish (approx. 18 x 30 cm), season with salt and pepper. Approx. 1⁄3 Spread the onion mixture on top. Place 2 more roulades on top and season. Continue until onions and meat are used up.
Knead the dough, roll out on a floured work surface slightly larger than the tin, place on top and press down slightly at the edges. Bake in a hot oven for about 1 1⁄4 hours. Cover with foil and bake for about 1 hour.
Tip: Where to put the rest? You can use the other half of the bread mix to bake rolls for the next breakfast. To do this, mix the mixture with water as described in the recipe and let it rise. Form into 6-8 rolls and let them rise for another 45 minutes. Bake in the preheated oven (electric cooker: 180 °C) for 15-20 minutes.