Clean the spinach, wash thoroughly and drain well in a sieve. Peel and finely chop the onions. Peel garlic and chop very finely. Heat 2 tablespoons of oil in a large saucepan, add half of the onions and half of the garlic and fry.
Add the spinach and let it collapse. Season with salt, pepper and nutmeg. Pour into a sieve and drain. In the meantime clean, wash and finely dice the carrots. Heat 2 tablespoons of oil in a frying pan, fry the remaining onions, garlic and carrots in it.
Add tomato paste and sauté briefly. Deglaze with stock and tomatoes, bring to the boil, simmer at low heat for about 5 minutes. Then season to taste with salt, pepper, paprika and sugar. Grease an ovenproof dish, add about 1/3 of the spinach.
Squeeze the rest of the spinach well and chop finely. Put the ricotta in a mixing bowl and stir in the chopped spinach. Pour into a piping bag without spout and squirt directly into the cannelloni. Pour onto the spinach in the casserole dish.
Spread tomato sauce over it and sprinkle with parmesan. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 40-45 minutes. Cover if necessary. In the meantime, roast pine nuts in a pan without fat.
Sprinkle the casserole with pine nuts and serve garnished with basil as desired.