01 - Preheat oven to 400°F (200°C). Line a baking tray with parchment paper.
02 - In a large bowl, gently combine ground turkey, egg, breadcrumbs, milk, parsley, garlic, onion, oregano, salt, and black pepper until just incorporated. Avoid overmixing.
03 - Divide the meat mixture into 12 equal portions. Flatten each portion in your palm, place a cube of mozzarella in the center, and carefully enclose the cheese with the meat, forming sealed balls.
04 - Place the formed meatballs evenly on the prepared baking tray.
05 - Bake for 20–25 minutes, or until cooked through and golden brown on all sides.
06 - While the meatballs bake, gently warm the marinara sauce in a saucepan over medium heat.
07 - Serve the hot meatballs over the warmed marinara sauce. Garnish with fresh basil, if desired.