Coarsely dice the fat. Knead flour, fat, 1 egg, 3 tablespoons water, 3 tablespoons milk and salt to a smooth dough. Cover and put in a cool place for about 30 minutes. In the meantime peel and finely dice the onions.
Cut the ham into fine cubes as well. Heat the oil in a pan and fry the onions for about 10 minutes at medium heat. In the meantime, grate the Gruyère cheese coarsely. Stir cream, remaining milk, remaining eggs and egg yolks until smooth and season with salt and nutmeg.
Add ham to the onions, season with salt and pepper. Take out and let cool down. Wash parsley and marjoram, dab dry and pluck. Put some marjoram aside for garnishing. Finely chop remaining herbs.
Roll out the dough on a floured work surface until round (approx. 32 cm Ø). Pour the dough into a greased tart tin (approx. 26 cm Ø) and remove the excess rim. Mix the onion and ham mixture with cheese and herbs and put into the tart tin.
Add the egg-milk-cream mixture. Bake in the preheated oven (electric oven: 175 °C/ gas: level 2) on the lower rack for about 1 hour. Take out, let cool down for about 15 minutes. Arrange on a plate and serve the ##Quiche Lorraine## garnished with marjoram.