Ricotta Gnocchi with Simple Tomato Sauce

1. To prepare the gnocchi, gently mix the cheese, egg yolks, salt, and nutmeg in a large bowl until blended.
2. Using your hands, fold the flour gradually into the cheese mixture. You may need more or less flour, depending on how well the cheese was drained. Work the dough until it forms a loose ball. Turn out onto a lightly floured surface and knead once or twice. Divide the dough into 4 pieces and roll each one into a long rope about 3/4 inch in diameter. Lightly dust each rope with flour to prevent sticking when you cut them into gnocchi.
3. Line a baking sheet with parchment paper and lightly dust it with flour. Cut the ropes into 3/4-inch-long pieces and transfer each piece to the baking sheet.
4. You may choose to leave the gnocchi in these pieces or go one step further by rolling each piece into a ball. Use your thumb, the back of a fork, or a small gnocchi paddle to make grooves on 1 side of the balls and a small indentation on the other.
5.Transfer the gnocchi to the baking sheet and refrigerate, uncovered, for up to 24 hours. (Do not cover with a damp cloth or the gnocchi will soften.) After the gnocchi dry for 24 hours in the refrigerator, they can be transferred to a rigid plastic container and frozen for up to 1 week. Let them thaw before cooking.
6. Fill a large saucepan with lightly salted water and bring to a boil over high heat. Gently drop the gnocchi into the water and cook for about 2 minutes, or until the gnocchi bob to the surface. When they do, cook for 1 minute longer and then drain, reserving about 1/4 cup of the pasta water.
7. To prepare the tomato sauce, heat the tomatoes over medium-high heat. Thin or loosen with a little pasta water. Stir in 1/2 cup of olive oil and the butter until the butter is incorporated. Toss the gnocchi with the tomato sauce. Stir in the parsley and season to taste with salt and pepper.
8. Divide the gnocchi among 4 serving plates and drizzle with olive oil.