Stir milk, eggs and flour until smooth. Season with salt and nutmeg. Let the dough swell for about 10 minutes
Peel the onion. Finely dice onion and bacon. Heat 2 tablespoons of oil in a large frying pan. Leave the bacon in it until crispy. Fry the onion in it. Clean, wash and slice the mushrooms. Steam briefly. Stir in crème fraiche and simmer for about 3 minutes. Grate cheese, fold in half. Seasoning
Coat a coated pan with oil. Bake 6-8 thin pancakes from the dough. Put them in a casserole dish. Fill with 2/3 of the mushroom ragout and roll up. Spread the rest of the ragout and cheese over it. Bake in a preheated oven (electric range: 200°C/circulating air: 175°C/gas: level 2) for 10-15 minutes until golden brown