Ricotta cheese cannelloni

Boil the spinach. Drain the spinach and pound it with a knife to make a paste. Add the spinach, ricotta cheese, Parmesan cheese, egg yolk, salt and pepper to a bowl and mix well with a spatula

Boil three lasagna slices, rinse in water, and drain. If the bechamel sauce is thick, heat it up

Cut the lasagna in half horizontally, place the 6 equal pieces of [1] on top, and roll it up from the front

Make sure the end of the wrapping is facing downwards. (Be careful not to wrap it too tightly as it may tear.)

Spread a moderate amount of melted butter on a gratin dish, and then top with the tomato sauce, the three cannelloni pieces from [4], the béchamel sauce, Parmesan cheese, tomato sauce, and Parmesan cheese in that order. Repeat with the other dish

Bake in the oven for about 15 minutes and it's done