• Heat the butter and vegetable oil in a large heavy bottom pot or Dutch oven over medium heat. Add the onion, carrot and celery and sauté until soft but not brown. Add the tomato paste and stir until all the vegetables are coated and the paste darkens in color, about 3 to 4 minutes.
• Next add the ground meat and season with salt. Crumble the meat as it cooks breaking it apart into tiny pieces. Cook and crumble the meat until no longer pink but not browned.
• Pour in the milk and bring to a simmer, stirring occasionally, until the milk evaporates and only clear fat remains, about 15 minutes. Add the wine and reduce the heat to medium low. Bring to a low simmer. Continue cooking and smashing the beef with a wooden spoon until the wine evaporates and the surface of the pot is almost dry, about 15 minutes. The beef should be finely ground and reduced to little bits.
• Add the tomatoes with juice, nutmeg and pepper and bring to simmer. Reduce the heat to the lowest setting so the sauce barely simmers with an occasional bubble or two at the surface until all liquid has evaporated, about 3 hours. It should look like a sloppy Joe mixture.
• Check the seasoning and add salt if needed. At this point the sauce can be refrigerated for several days or frozen for up to two months. Rewarm over low heat before serving.

To serve:

• Prepare the rigatoni according to package directions. Don’t drain the pasta but instead use a slotted spoon to transfer the damp pasta to the sauce. Add the Parmesan and if needed add a little pasta cooking water will help to loosen the sauce slightly. Divide the Rigatoni Bolognese into individual servings or spoon onto one large platter. Top with additional fresh grated Parmesan and parsley. Serve immediately.