Preheat your oven to 400 degrees F. Line a large baking sheet with parchment paper and lightly grease it with olive oil.
In a large bowl, combine the ground turkey, breadcrumbs, grated parmesan, eggs, minced garlic, Italian seasoning, salt, black pepper, and 1 tablespoon of the fresh parsley. Mix gently with your hands until just combined. Do not overmix or the meatballs will become dense.
Scoop and roll the mixture into about 20 meatballs, roughly 2 tablespoons each. Place them on the prepared baking sheet with a little space between each one.
Bake for 18 to 20 minutes until the meatballs are golden on the outside and cooked through to an internal temperature of 165 degrees F.
Pour the marinara sauce into a large oven-safe skillet or baking dish. Nestle the baked meatballs into the sauce and top with shredded mozzarella cheese.
Return to the oven and bake for 8 to 10 minutes until the cheese is melted, bubbly, and lightly golden.
Sprinkle the remaining fresh parsley over the top. Serve the meatballs as is, or with crusty bread or over spaghetti.