Gnudi means, well, “nude” — because these are nude ravioli, the filling without the outer pasta covering. They are delicious served with tomato sauce, as in this recipe, or with melted butter and sage.
In a large bowl, combine the spinach, ricotta, pecorino, and egg yolks. Stir to blend. Stir in the nutmeg and salt to taste, then gently stir in the flour, mixing just enough to pull the mixture together.
Bring a large pot of salted water to a boil. Heat the tomato sauce and spread a thin layer of it over the bottom of a 9-by-13-inch baking dish. Set aside.
Using two tablespoons, shape and compact the ricotta mixture into ovals and drop them directly
into the boiling water in batches, so as not to crowd the pot. They will float to the top when done, after 3-4 minutes. Using a wire skimmer or slotted spoon, transfer the gnudi to the casserole dish. Keep warm in a low oven. Repeat to cook all the remaining gnudi. Spoon the remaining tomato sauce over the gnudi and serve at once.