Mix eggs, 3/8 litres of milk, 200 grams of flour and 1/2 teaspoon of salt to a smooth dough. Cover and leave to swell for 30 minutes. Meanwhile clean, wash and slice the leek.
Cook in boiling salted water for five minutes, drain and collect the vegetable water. Cut the bacon into fine cubes and drain them crisply in hot oil. Add remaining flour and sweat briefly.
Add 200 millilitres of leek water and the remaining milk while stirring. Bring to the boil and simmer for about five minutes. Wash parsley and thyme, dab dry and chop except for a little bit for garnishing.
Stir the herbs into the sauce, season with salt and pepper and keep warm. Stir mineral water into the pancake batter. Heat some fat in a large pan (23-24 cm Ø). Add 1/4 of the batter and sprinkle with leek.
Bake pancakes from both sides until golden brown. Slide onto a preheated plate and keep warm. Bake three more pancakes one after the other. Pour sauce over the pancakes and serve garnished with parsley.