Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large bowl, combine the ground turkey, breadcrumbs, Parmesan cheese, parsley, onion, garlic, egg, salt, pepper, oregano, basil, and red pepper flakes (if using). Mix until just combined; do not overmix.
Using your hands, form the mixture into meatballs, about 1 to 1.5 inches in diameter, and place them on the prepared baking sheet.
Bake the meatballs in the preheated oven for 20-25 minutes or until they are cooked through and golden brown.
While the meatballs are baking, heat the marinara sauce in a small saucepan over medium heat.
Serve the meatballs warm, topped with marinara sauce.