In the meantime, prepare the filling: put the ricotta in a container, add the boiled and cut chard, along with the grated Parmigiano Reggiano, egg and salt and mix everything together with the grated nutmeg.
Roll out the pasta with a rolling pin to obtain a thin sheet. Place the pasta on a work surface and place a teaspoon of filling (for each tortello) on top and then cover it with the pasta, try not to leave any air holes that could cause the tortello to break up during cooking.
Prepare a dish that has some knobs of butter on the bottom, place the well-draned tortelli on top and cover with a layer of Parmigiano Reggiano on top.
Finely dice the celery, carrot and onion, dice the zucchini and asparagus. Melt the butter in a pan and sauté the vegetables over low heat, season with salt and pepper.
Cook the lasagna sheets in boiling salted water for a short while and then rinse them in cold water. Pat dry with a cloth.
Cut the prosciutto crudo into thin strips.
Cover the bottom of a baking dish with a thin layer of bechamel sauce and cover with lasagne sheets, sprinkle with prosciutto crudo and vegetables and cover with another layer of bechamel sauce. Sprinkle with Parmigiano Reggiano. Repeat the process until all pasta sheets, vegetables and prosciutto crudo are used up.
As a last layer, use the remaining béchamel sauce with the tomato sauce and sprinkle with the remaining Parmigiano Reggiano.