Preheat your oven to 400°F (200°C).
In a large bowl, combine ground beef and pork.
Add breadcrumbs, Parmesan cheese, parsley, garlic, egg, salt, pepper, and red pepper flakes to the meat.
Mix everything together until well combined.
Form the mixture into 1-inch meatballs and place them on a baking sheet.
Bake meatballs in the preheated oven for 20 minutes or until browned.
While meatballs are baking, heat marinara sauce in a saucepan.
Once meatballs are cooked, add them to the marinara sauce and simmer for 5 minutes.
Serve over spaghetti or your favorite pasta.
Garnish with additional parsley or cheese, if desired.