Wash and clean the spinach. Peel onion and garlic and chop finely. Heat 2 tablespoons of oil in a high frying pan. Fry half of the onion and garlic for about 2 minutes until transparent. Deglaze with 100 ml broth.
Add half the spinach and cook for about 3 minutes while stirring. Season with salt, pepper and nutmeg, take out. Heat 2 tablespoons of oil in a frying pan. Sauté the rest of the onion and garlic, add 100 ml broth and cook the rest of the spinach in it.
Season with salt, pepper and nutmeg, take out. Put the spinach in a sieve, drain and let it cool down. Put the pizza dough with baking paper on a baking tray and let it rest for about 10 minutes at room temperature.
Squeeze the spinach well. Crumble cheese. Mix egg, lemon rind, breadcrumbs, half sheep's cheese, cream cheese and spinach. Season to taste with salt and pepper. Roll out the dough on a baking tray, cut in half lengthwise and prick several times.
Spread the spinach filling in the middle as a strand. Fold down the long sides approx. 1 cm. Mix egg yolk and milk. Coat the edges of the dough with it. Fold up both long sides so that the spinach is firmly enclosed by the dough on the sides.
Twist both ends and press on. Sprinkle spinach with the remaining feta cheese. Spread the outer edges of the dough with egg yolk-milk mixture. Bake in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for 15-20 minutes, remove from oven.