Cook the vegetables. Add a tablespoon of olive oil to a medium sized pan over medium heat. Add the prosciutto to the pan and cook it until it's browned. Add the onion, celery, carrot, mushrooms, and garlic to the pan and sauté for 5 minutes.
Cook the meats. Simotanesouly while the vegetables are cooking, add 2 tablespoons of olive oil to a large pot over medium heat. Add the ground beef, pork, and veal to the pot and cook until it is done. Add the red wine to deglaze the pan, then cook until it is nearly evaporated (about 5 minutes).
Add the seasoning. Once the wine has evaporated from the meat pan, add the parsley, marjoram, nutmeg, sugar, and salt. Stir to combine. Add the sautéd vegetables to the meat pot. Pour the beef broth and tomato paste in to the pot, then stir.
Simmer the sauce. Add the milk to a separate pot and bring it to a light boil. Slowly add the milk to the sauce, then bring the sauce to a light boil. Reduce the sauce to a simmer. Allow the sauce to simmer for at least 45 minutes, or up to three hours. Cook the pasta according to package instructions in generously salted water. Reserve 1/2 cup of the pasta water before draining. Add the pasta water to the sauce, stir, then serve over the pasta. Mangia!