This dish is also known as naked ravioli because the gnocchi are essentially buttery mounds of ravioli filling. It's important to squeeze the spinach completely dry, so the gnocchi don't fall apart.Plus: Pasta Recipes and Tips
Bring a large pot of water to a boil. Add one-third of the spinach and boil just until wilted. Using a slotted spoon, transfer the spinach to a colander and let cool under running water. Repeat with the remaining spinach. Squeeze the spinach as dry as possible.
Finely chop the cooked spinach and transfer it to a large bowl. Add the egg yolks, ricotta, 1 1/2 cups of the Parmesan, 1/2 cup of the flour, the salt, pepper, grated lemon zest and nutmeg. Stir to form a soft dough.
Divide the dough into 8 pieces. On a lightly floured surface, roll each piece of dough into a 1-inch-thick rope. Cut the rope into 1-inch pieces. Using floured hands, roll the pieces into balls and flatten slightly. Transfer the gnocchi to a generously floured rimmed baking sheet.
Bring a large pot of salted water to a boil. Pour half of the melted butter into a large baking dish. Add one-fourth of the gnocchi to the boiling water, gently stir once and let the gnocchi rise to the surface. Simmer the gnocchi until tender and cooked through, 2 to 3 minutes. Using a slotted spoon, transfer the gnocchi to the buttered baking dish. Cover with foil and cook the remaining gnocchi in batches. Reserve 1/2 cup of the cooking water.
In a large, deep skillet, combine the remaining 4 tablespoons of melted butter and 1/2 cup of Parmesan with the reserved gnocchi cooking water and simmer over moderate heat until slightly thickened, about 4 minutes. Pour the sauce over the gnocchi and toss to coat. Sprinkle with additional Parmesan and serve right away.
The gnocchi can be prepared through Step 3 and refrigerated overnight.
A light, fruity red from Piedmont will blend with the rich gnocchi without overwhelming them. Or consider a bright, round, creamy-textured Chardonnay from Tuscany.