Wash the potatoes thoroughly, grate them dry and cut off the pointed ends. Slice the potatoes into thin slices. Line a springform pan (26 cm Ø) with baking paper. Cover the bottom with about 1/2 potato slices.
Peel and finely dice or chop the onion and garlic.
Heat 2 tablespoons of oil in portions in a large frying pan. Fry the minced meat in 2 portions until crumbly. Mix onion and garlic into the 2nd portion and fry for about 2 minutes. Mix the whole mince, season with salt and pepper and put aside.
Clean, wash and drain the spinach. Heat 1 tablespoon of oil in a large pot. Add the spinach and let it collapse. Season with salt and pepper. Spread the spinach on the potatoes.
Add the minced meat in a dome-like manner and spread the ricotta in patches over it. Cover with remaining potato slices.
Whisk egg and cream and spread on potatoes. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 40 minutes. Remove from the oven and carefully remove the minced cake from the tin.
Arrange and sprinkle with cress.