Preheat oven to 350 °F (177 °C) and line a rimmed baking sheet with parchment paper or a Silpat baking mat. Set aside.
Pour tomato sauce into 9x13” glass baking dish and spread in a thin layer to cover the bottom and set aside.
Add ground turkey, eggs, Parmesan cheese, oregano, basil, parsley, garlic, onion salt, and crushed red pepper flakes in a large glass bowl. Season with salt and black pepper, to taste. Thoroughly combine mixture with your hands and divide into 24 equal-sized portions. (For larger meatballs, separate into 18 pieces). Add more Parmesan cheese, if necessary, to bind the ingredients.
Gently roll each portion into a ball and place on prepared baking sheet, leaving room between each meatball. Place baking sheet in the preheated oven and bake for 15-20 minutes. Remove from oven and transfer meatballs to a prepared baking dish. Drizzle with additional tomato sauce and Parmesan cheese, if desired.
Place baking dish in the oven for approximately 10 minutes, or until sauce and meatballs are heated throughout, Remove from oven and serve immediately with additional tomato sauce, Parmesan cheese, and fresh basil if desired.
Notes
Tip: To help the meatballs hold their round shape, bake them on their own first before adding the tomato sauce. Optional: Additional tomato sauce, Parmesan cheese, and fresh basil for serving.