Heat a little oil in a large pot, add the osso buco and brown on all sides. Remove the meat from heat and set aside. Add more a little more oil and the butter to the pot. Add the onions, carrots, celery, garlic, and rosemary, and cook a few minutes until golden. Return the meat to the pot and add the prunes and red wine. Cook until the alcohol evaporates, and then add the beef stock and soy sauce. Cover and cook over very low heat for 2 ½ hours or until the meat is very tender.
Mound the flour in a bowl, make a well in the center, and add the egg and egg yolks. Mix well to form a dough, and then knead until the dough is very smooth and elastic, about 10 minutes. Cover the dough with plastic wrap and allow to rest in the refrigerator for at least 30 minutes.
Preheat the oven to 150ºC. Place the Serrano ham on a baking sheet and bake for 10 minutes or until crisp but not browned. Set aside.
Once the meat is very tender, allow it to cool and then shred it with your hands into very small pieces, adding a few tablespoons of the cooking liquid as needed to keep it moist.
Place the remaining cooking liquid and vegetables in a blender and process until very smooth. Strain the liquid through a fine-meshed strainer and set aside. Reheat before serving.
Roll the fresh pasta dough out very thin. Lay a sheet out flat and spoon small amounts of the meat in two rows. The amount used will depend on the desired size of the ravioli. Use a brush dampened with a little water to lightly moisten another thin sheet of dough and place it on top of the sheet with the filling, pressing around the filling to remove as much air as possible. Press firmly around the dough to seal the two layers of dough. Use a pastry cutter or knife to cut the individual ravioli into 4- or 5-cm squares, making sure that the two layers are tightly joined so that they don’t open during cooking. Place the ravioli on a tray that has been dusted well with semolina flour to keep them from sticking.
Cook the ravioli in abundant boiling salted water for 3 minutes. Drain well and place in a large skillet with the hot sauce.
Serve the ravioli with the warm sauce, garnished with the crisp ham chips, finely chopped chives, and Parmesan cheese.