Cut the onion into small cubes.
Fry it in olive oil for 3-4 minutes (transparent color).
Put the whole stuffing and fry for 10 minutes.
Pour into broth, add greens.
Simmer for 10–15 minutes under a lid, until evaporation.
Transfer to a bowl, mix with ricotta and one egg.
Add hard cheese for thickening, if required.
Brush the bottom of the pan with tomato sauce.
Stuff the cannelloni with the mixture (you can use a pastry bag or a spoon for this). Then they are firmly folded to each other and pour the remaining red sauce on top.
Cover with foil, bake for 30 minutes at 200 degrees.
Top with cheese and decorate in the oven for another few minutes.