Mix 100 g butter, flour, salt and 1 egg first with the dough hooks of the hand mixer, then with your hands to a smooth dough. Wrap the dough in foil and chill for approx. 30 minutes
Prepare rice in boiling salted water according to package instructions. Wash and sort the spinach leaves and drain well. Clean and wash the leek and cut into fine strips. Heat 1 tablespoon butter in a pan and steam the leek for about 5 minutes. Add the spinach about 3 minutes before the end of the cooking time. Season vegetables with salt, pepper and nutmeg, remove from the pot and drain if necessary
Grate parmesan. Mix 2 eggs, ricotta, rice and oregano. Add 2/3 of the parmesan, season with salt and pepper. Roll out the dough on a floured work surface and cut out approx. 8 circles (approx. 12 cm Ø), kneading the rest again
Grease tartlets (approx. 10 cm Ø) and line with dough. Prick several times with a fork and spread the spinach mixture on top. Pour the ricotta mixture over it and sprinkle with the rest of the Parmesan cheese. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for 30-40 minutes until golden brown. Take out and serve
Waiting time approx. 30 minutes