Preheat the Oven: Set your oven to 400 degrees and place the rack in the lower 1/3.
Mix Ingredients: In a large bowl, combine the grated onion, chopped parsley, Parmesan cheese, Italian bread crumbs, egg, 2 tablespoons of marinara sauce, minced garlic, red pepper flakes, salt, and pepper.
Add Ground Beef: Once mixed, add the ground beef to the bowl. Use your hands to mix everything thoroughly.
Shape Meatballs: Shape the mixture into 16 meatballs. Ensure they are evenly sized for consistent cooking.
Insert Mozzarella: Make a hole in the center of each meatball and place a cube of mozzarella inside. Reform the meatball to fully conceal the cheese.
Prepare Baking Dish: Spoon 1/3 cup of marinara sauce into the bottom of a baking dish.
Arrange Meatballs: Place the meatballs in the baking dish. Drizzle a little extra virgin olive oil over the top.
Bake: Bake in the preheated oven for 15 minutes or until the meatballs are cooked through.
Enjoy: Once done, take them out, and savor the delightful Baked Mozzarella Stuffed Meatballs!
