Add the milk and breadcrumbs to a large mixing bowl and stir to combine.
Add the the beef, pork, prosciutto, eggs, Parmesan, parsley, basil, oregano, and garlic to the breadcrumb mixture. Season with salt and pepper. Use your hands to blend the mixture, being careful not to over-mix.
Divide the mixture into ¼ cup (88g) portions and roll into balls. Place them on a baking sheet until all the mixture is used.
In a large skillet over medium heat add 2 tablespoons of the olive oil (26g) and heat through. Working in two batches, add half of the meatballs to the skillet and cook turning frequently, until browned on all sides and cooked through, about 8 minutes.
Remove the meatballs to a plate. Add the remaining olive oil to the pan and repeat with the remaining meatballs.
Warm the marinara sauce in a pot or pan then add the meatballs and simmer turning in the sauce.
Bring a large pot of water to the boil. Add the pasta and cook, stirring occasionally, until al dente, about 10 minutes. Drain and return the pasta to the pot and toss with ladles of the marinara sauce.
Serve the meatballs hot over the spaghetti and marinara and top with ladles of sauce. Garnish with cheese. Serve hot.