Preheat your oven to 400°F. Line a baking sheet with parchment paper.
In a large bowl, combine the ground pork, breadcrumbs, Parmesan cheese, parsley, egg, garlic, salt, pepper, oregano, and onion powder. Mix until well combined.
Using your hands, form the mixture into meatballs about 1.5 inches in diameter and place them on the prepared baking sheet.
Bake the meatballs in the preheated oven for 20 minutes, or until they are cooked through and browned.
Remove the meatballs from the oven and pour the marinara sauce over them. Sprinkle the shredded mozzarella cheese on top.
Return the baking sheet to the oven and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
Let the meatballs cool for a few minutes before serving.