Put flour, fat, 1/2 teaspoon salt, 1 egg and 1-2 tablespoons water into a mixing bowl. Knead with the dough hook of the hand mixer. Then work into a smooth dough with cool hands. Cover and leave to rest in the refrigerator for approx. 30 minutes. In the meantime clean, wash and cut the leek into rings.
Heat the oil in a pan and fry the leek for about 5 minutes at low heat. Season with salt and pepper. Roll out the dough 4-5 mm thick on a lightly floured work surface and cut out circles (approx. 14 cm Ø). Grease 6 moulds (approx. 12 cm Ø) with lift-off bases and line with the dough. Spread leek on top. Mix crème fraiche and remaining eggs and season with salt, pepper and nutmeg. Grate cheese finely. Stir about 50 g into the egg crème fraiche and pour over the leek. Sprinkle with remaining cheese and bake in the preheated oven (electric oven: 200 °C/ gas: level 3) on the second rack from the bottom for 25-30 minutes.
Spread leek on top. Mix crème fraiche and remaining eggs and season with salt, pepper and nutmeg. Grate cheese finely. Stir about 50 g into the egg crème fraiche and pour over the leek. Sprinkle with remaining cheese and bake in the preheated oven (electric oven: 200 °C/ gas: level 3) on the second rack from the bottom for 25-30 minutes. Take out of the moulds and serve