In a large bowl, combine ground beef, ground pork, breadcrumbs, Parmesan cheese, parsley, eggs, minced garlic, salt, black pepper, and red pepper flakes. Mix until well combined. Form the mixture into meatballs, about 1.5 inches in diameter.
Heat olive oil in a large skillet over medium heat. Add meatballs in batches and brown on all sides, about 5-7 minutes. Remove meatballs and set aside.
In the same skillet, pour in red wine and scrape up any browned bits from the bottom. Add crushed tomatoes and beef broth, stirring to combine. Return meatballs to the skillet, cover, and simmer for 30 minutes.
While the meatballs are simmering, bring 4 cups of water to a boil in a separate pot. Gradually whisk in polenta and reduce heat to low. Cook for about 15 minutes, stirring frequently until thickened. Stir in mozzarella cheese, milk, garlic powder, salt, and pepper.
Serve meatballs over a generous scoop of cheesy polenta. Spoon extra sauce over the top.