In a large bowl, combine the ground beef, ground pork, ground veal, bread crumbs, Parmesan cheese, parsley, garlic, egg, milk, salt, black pepper, and dried oregano. Mix well.

Shape the mixture into meatballs, about 1 to 2 inches in diameter.

Heat oil in a large skillet over medium heat. Add the meatballs and cook until browned on all sides.

Remove the meatballs from the skillet and set aside.

In the same skillet, add the marinara sauce and bring to a simmer.

Add the meatballs back to the skillet and cook in the sauce for about 20 minutes, until the meatballs are cooked through.

Serve the meatballs with spaghetti or bread, and enjoy!