Defrost the spinach. Knead the flour, 2 eggs, 1/2 teaspoon salt, 200 g butter in pieces and 2-3 tablespoons water first with the dough hooks of the hand mixer, then with your hands to a smooth dough.
Cover and chill for approx. 30 minutes. Grate the Parmesan finely. Roast the pine nuts in a pan without fat until golden brown, take them out, let them cool down and put something aside for garnishing. Peel onion and garlic cloves and dice finely.
Heat 1 tablespoon of butter in a frying pan. Sauté the onion and garlic until translucent. Squeeze out the spinach, put it into the pan and stew it for about 2 minutes at low heat. Take it off the stove, grease the springform pan (26 cm Ø), dust it with flour and wrap the lower half with aluminium foil.
Roll out 2/3 of the dough round (approx. 34 cm Ø) on a work surface dusted with flour. Line a form with it, pressing the edge (approx. 4 cm high) well and straighten it. Prick the base of the dough several times with a fork and sprinkle with breadcrumbs.
Mix 2 eggs, pine nuts, spinach, ricotta and parmesan. Season to taste with salt, pepper and a little nutmeg. Put the spinach mixture into the mould. Press 6 depressions into the mixture. Add 6 egg yolks carefully.
Roll out the remaining dough on a floured work surface until round (approx. 28 cm Ø), place in the mould, cut off any excess dough and carefully press the lid on. Cut a round hole (5-6 cm Ø) in the middle.
Spread the cake with milk and bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 50-60 minutes until golden brown. About 20 minutes before the end of the baking time, brush the surface with the remaining milk.
Cover the last minutes of the cake if necessary. Wash the herbs, dab dry and chop finely. Mix yoghurt and sour cream, fold in herbs. Season to taste with salt, pepper and a little sugar.
Take out the cake, let it cool down briefly, cut it into pieces and arrange it. Sprinkle with remaining pine nuts. Add dip.