Defrost the spinach. Peel onions and cut into cubes. Melt the fat in a pot. Sauté half of the onion cubes in the hot fat until translucent. Add spinach and season with salt, pepper and nutmeg. Steam for about 5 minutes.
Put the spinach in a sieve. Let the liquid drain off. Pour the spinach back into the pot. Stir the ricotta into the spinach. Cook the lasagne sheets in a pot of boiling salted water for about 3 minutes. Carefully pour into a sieve and rinse with cold water. Fill the lasagne sheets with spinach and roll up into a roll. Pour into a greased casserole dish and sprinkle with cheese. Cook in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 30 minutes. In the meantime, heat oil for the tomato sauce. Fry the remaining onions in the fat until translucent. Add tomato paste and dust with flour.
Fill the lasagne sheets with spinach and roll up into a roll. Pour into a greased casserole dish and sprinkle with cheese. Cook in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 30 minutes. In the meantime, heat oil for the tomato sauce. Fry the remaining onions in the fat until translucent. Add tomato paste and dust with flour. Pour in broth, bring to the boil and season to taste with salt, pepper and sugar. Serve cannelloni with tomato sauce
30 minutes waiting time