Clean, wash and cut the savoy cabbage into very fine strips. Cut bacon into fine strips as well. Peel and chop the onion. Heat the oil in a pan. Fry the onion and bacon strips in it.
Add the savoy cabbage, braise and season with salt, pepper and nutmeg. Stir in 150 g crème fraîche and simmer for 2-3 minutes. Stir 75 g cheese into the savoy cabbage and let it melt. Remove from the heat and allow to cool.
In the meantime, precook the lasagne sheets in portions in boiling water for about 3 minutes. Rinse in cold water, cut in half lengthwise and place on a lightly oiled plate. Spread some savoy cabbage filling on each strip of pasta, roll it up and place it close together upright in a high, greased casserole dish.
Mix the stock and remaining crème fraîche and pour over the pasta snails. Close the casserole dish well with aluminium foil. Bake lasagna rolls in the preheated oven (electric: 200 °C/ gas: level 3) for 20-25 minutes.
Remove foil, sprinkle lasagne snails with remaining cheese and continue baking without foil for about 10 minutes.