Cook the pasta in boiling salted water for about 10 minutes, drain and allow to drain. Clean spinach, wash thoroughly. Peel onion and garlic and chop finely. Heat the oil in a pot. Sauté onion and garlic in it. Add the spinach dripping wet and let it collapse on top. Season with salt and pepper.
Mix spinach, ricotta and cream in a bowl. Stuff the pasta with it. Grease a large casserole dish and put the pasta in it. Sprinkle with parmesan. Gratinate in a preheated oven (electric cooker: 250 °C/ convection oven: 225 °C/ gas: level 5) for about 10 minutes. Serve hot immediately