Preparing the gnocchi:
Wash, boil and peel the potatoes while they are still warm, and pass them through a sieve. Mix in the flour with the egg yokes, knead the dough and let it sit for 10 minutes. Stretch out the dough to form strips 1 cm high and cut them length-wise every 3 cm. Press the gnocchi with a thumb on the tip of a fork. Bring a pot ful of water to boil and then throw in the gnocchi. The gnocchi are ready when they come up to the surface.
Preparing the sauce:
Cut the tomatoes cross-wise on the bottom, then boil them for 2 minutes, peel and slice them. Stir-fry the tomatoes on a light flame, until they start crumbling apart. Add the fresh, diced Pecorino Toscano and the water until you have a creamy mixture, then pour the cooked gnocchi on the cream and add the mascarpone. Mix the gnocchi and cream, add the seasoned Pecorino Toscano cut into thin slices, a few knobs of butter and bake in an oven at 200 °C, until a thin crust forms. Serve warm.