Steam the power greens in a steamer basket over boiling water until wilted, 1-2 minutes. Transfer the greens to a colander to drain. Once cool, squeeze out any remaining water and chop the greens.

Mix the greens, ricotta, egg yolks, Parmesan, salt, pepper and nutmeg together in a medium bowl until well combined. Stir in ½ cup flour until a sticky dough forms.

Pile the remaining cup of flour on a cutting board or plate. Using a small cookie scoop or a tablespoon, drop a ball of dough (slightly larger than the size of a walnut) onto the flour and lightly toss it around in the flour until coated. Gently form the dough into a ball with your hands, shaking off any excess flour. Repeat with the remaining dough. You should have about 24 gnudi in total. Discard the remaining flour. Place the gnudi on a sheet pan and chill in the fridge.

Bring a large pot of water to a boil then lower the heat to a simmer. Working in batches, drop the gnudi into the water. Cook them until they float to the surface of the water, about 4 minutes. Carefully remove them with a slotted spoon.

To serve, spoon some tomato sauce onto a serving platter and place the gnudi on top. Garnish with grated Parmesan cheese.