Mix flour, eggs, salt and milk with the whisk of the hand mixer to a smooth dough. Let it swell for about 10 minutes. Clean and wash the leek and cut into fine rings. Cut bacon into pieces.
Heat up a pan (24 cm Ø). Add 1/8 of the bacon and leek, add 1/8 of the dough and fry over medium heat for 4-5 minutes on each side. Remove and keep warm in the oven.
Process remaining ingredients in the same way. Sprinkle crème fraîche with pepper.