Dice butter. Knead flour, butter, 2 eggs, 4-5 tablespoons cold water and 1/2 teaspoon salt to a smooth dough. Cover the dough and chill for about 1 hour. Peel onions and cut into rings. Heat the oil in a large pan and fry the onion rings for about 5 minutes while turning.
Mix sour cream, sour cream and 3 eggs. Season with salt, pepper and nutmeg. Roll out the dough to a rectangle (34 x 41 cm) on a floured work surface. Place the dough on a greased baking tray (32 x 39 cm) and press the rim up a little. Spread the onions on top. Pour egg milk over it. Spread slices of bacon on top. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 30 minutes. Wash the thyme, dab dry and pluck the leaves from the stalks.
Spread the onions on top. Pour egg milk over it. Spread slices of bacon on top. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 30 minutes. Wash the thyme, dab dry and pluck the leaves from the stalks. Sprinkle over the onion cake
Waiting time approx. 30 minutes