How to Make It
Preheat the oven to 450°. Cut the center strip of the spareribs into individual riblets and set on a baking sheet. Cut each outer strip into 3 equal pieces and add to the baking sheet. Drizzle the ribs with 2 tablespoons of the oil, season with salt and pepper and turn to coat. Roast until golden, 20 minutes. Let cool slightly, then tie the individual ribs in a cheesecloth bundle.
In a large enameled cast-iron casserole, heat 2 tablespoons of the oil. Add the onion, carrots, celery, garlic, thyme and pork skin, if using. Cook over moderate heat, stirring, until the vegetables are softened, 15 minutes. Add the wine and cook until reduced by half, 5 minutes. Stir in the tomatoes, 2 cups of water and the roasted rib strips and bring to a simmer. Cook over low heat for 45 minutes, stirring occasionally. Add the cheesecloth rib bundle. Cook, stirring, until the sauce is thick and all the ribs are tender, about 1 hour longer. Remove the cheesecloth bundle and reserve the riblets.
Transfer the rib strips to a work surface and remove the meat from the bones. Add the meat to the ragù; discard the bones.
In a large pot of salted boiling water, cook the pasta until al dente. Drain, reserving 1 cup of the pasta water. Return the pasta to the pot and add the reserved water, the ragù, the remaining 1 tablespoon of olive oil and the 1 cup of grated cheese. Season with salt and pepper and toss until well coated. Mound the pasta in bowls, garnish with the riblets and serve, passing additional cheese at the table.