Mix flour and baking powder. Mix with eggs, milk and 1 pinch of salt until smooth. Leave to swell for approx. 15 minutes
Clean and wash the savoy cabbage and cut into fine strips. Peel and finely chop the onions. Heat 2 tablespoons of butter. Fry savoy cabbage and 3/4 onions in it, season. Deglaze with 100 ml water, bring to the boil. Cover and stew for about 10 minutes. Season to taste and drain if necessary
Stir mineral water into the dough. Heat the oil in portions in a pan (24-26 cm Ø). Bake 6 pancakes from the dough in it one after the other until golden brown
In the meantime press the sausage mass out of the skin. Spread 5 pancakes thinly one after the other and alternate layers of savoy cabbage on a baking tray lined with baking paper. Cover with the uncoated pancake. Bake in a hot oven (electric cooker: 175 °C/ convection oven: 150 °C/gas: level 2) for approx. 30 minutes
Clean mushrooms, wash if necessary. Drain and cut into small pieces. Sauté the rest of the onions in 1 tbsp. hot butter, season with salt and pepper. Deglaze with 1/4 l water and cream, bring to the boil. Stir in stock and sauce thickener, simmer for about 1 minute. Season to taste. Serve everything