In a large mixing bowl, combine the ground turkey, chopped spinach, breadcrumbs, Parmesan cheese, chopped onion, minced garlic, egg, dried oregano, salt, black pepper, and red pepper flakes (if using).
Using your hands, mix all the ingredients thoroughly until well combined. Avoid over-mixing to keep the meatballs tender.
Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
With wet 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 about 20 minutes, or until they are cooked through and golden brown.
While the meatballs are baking, heat the olive oil in a large skillet over medium heat. Add the marinara sauce and let it simmer until heated through.
Once the meatballs are done, add them to the skillet with the marinara sauce, gently tossing to coat them in the sauce. Let them simmer together for about 5 minutes.
Serve the meatballs hot, garnished with additional grated Parmesan and fresh basil if desired.
Notes
Serve with additional grated Parmesan and fresh basil if desired.