In a large bowl, mix ricotta, spinach, Parmesan cheese, eggs, and yolks. Stir in nutmeg, salt, pepper, and flour. Form mixture in to small, flattened balls. Dredge the formed gnudi in flour to coat, tapping off the excess.
Remove the gnudi using a slotted spoon after they float to the top and have cooked for about 4 minutes. Arrange gnudi on a platter and lightly drizzle with marinara sauce.
This classic gnudi recipe is served with a warming sage and brown butter sauce, the perfect accompaniment to these beautiful ricotta-based dumplings. If you fancy serving the gnudi with something else, simply pan-fry after boiling for a crispy, golden exterior, or leave them plain and serve with your choice of sauce.