Drain the ricotta by either placing it in a sieve over a bowl for 30 min, or by squeezing the ricotta with a clean kitchen towel.
Into a bowl, add the drained ricotta, egg yolk, flour, finely grated parmesan, nutmeg, salt and black pepper. Knead it into a dough. If the dough is toooo sticky, add a little bit more flour, but not too much. Shape into a ball, cover it with plastic wrap and let it sit in the refrigerator for 30 min. Meanwhile make the tomato sauce.
Peel and cut yellow onion and garlic into chunks.
Into a pot, add crushed tomatos, water, yellow onion, garlic, fresh basil, bay leaf and sugar. Let come to a simmer and let simmer on low for about 40 min.
Divide the ricotta dough into 4 pieces. On a floured surface, roll them into ropes (about 2.5 cm in diameter). Then cut them into 1 cm pieces. Place the pieces on a floured surface and dust them with more flour if they are too sticky.
Using a gnocchi board or the back of a fork, gently roll each ricotta ball along the lines to create the beautiful gnocchi shape.
Remove the bay leaf from the tomato sauce and blend the sauce smooth using a stand mixer. If you want the sauce to be thinner, add some water.
Add shredded mozzarella to the tomato sauce and let it melt into the sauce.
Season the tomato sauce with salt and black pepper.
Bring a pot of salted water to a boil and cook the ricotta gnocchis for about 5 min. They should float to the top.
Transfer the gnocchis to the pasta sauce and toss.
Serve and top with some extra parmesan cheese.
