In a large mixing bowl, combine ground beef, ground pork (if using), breadcrumbs, Parmesan cheese, pesto, garlic powder, onion powder, salt, pepper, and the beaten egg. Mix until all ingredients are well incorporated.
Take a small amount of the meat mixture (about the size of a golf ball) and flatten it in your palm. Place a mozzarella ball in the center. Carefully fold the meat around the cheese and shape it back into a ball, ensuring the cheese is completely enclosed. Repeat this process until all the meat mixture is used.
Place the stuffed meatballs on a baking sheet lined with parchment paper.
Bake in the preheated oven for 20-25 minutes, or until the meatballs are cooked through and browned on the outside.
While the meatballs are baking, heat the marinara sauce over low heat in a small saucepan.
Once the meatballs are done, remove them from the oven, and let them sit for a couple of minutes.
Serve the meatballs drizzled with warm marinara sauce and garnish with fresh basil leaves.
Notes
You can replace ground pork with more ground beef if desired.