In a mixing bowl, combine the ground turkey, Italian breadcrumbs, Parmesan cheese, egg, garlic powder, onion powder, salt, and pepper. Mix until just combined. Use a cookie scoop or tablespoon to form the mixture into uniform meatballs and place them onto a plate.
Heat a large skillet over medium heat and lightly coat it with oil. Brown the meatballs for about 5-7 minutes, turning them gently to brown on all sides. They do not need to be fully cooked at this point, as they will finish cooking in the oven.
Spread a thin layer of marinara sauce at the bottom of a medium sized casserole dish. Arrange the meatballs on top of the sauce. Pour the remaining marinara sauce over the meatballs, ensuring they are well-coated.
Sprinkle the shredded mozzarella and grated Parmesan evenly over the top of the casserole.
Place the baking dish in the preheated oven and bake for 25-30 minutes, until the cheese is melted and bubbly and the meatballs are fully cooked through (internal temperature should reach 165°F).
Remove from the oven and let it cool for 5 minutes. Sprinkle freshly chopped parsley over the top and serve