Prep the zucchini: Grate the zucchini on the small holes of a box grater. Place it in a clean kitchen towel and squeeze hard to remove excess moisture.
You want it as dry as possible so the meatballs hold together.
Make the mixture: In a large bowl, combine ground turkey, dried zucchini, onion, garlic, Parmesan, egg, parsley, Italian seasoning, salt, pepper, and red pepper flakes. Mix gently with your hands or a fork. Don’t overwork it or the meatballs will be tough.
Form the meatballs: Use a cookie scoop or spoon to portion 18–20 meatballs, about 1.5 inches each.
Roll lightly with damp hands to smooth.
Heat the pan: Warm a large skillet over medium heat. Add olive oil and let it shimmer.
Sear the meatballs: Add meatballs in a single layer without crowding. Sear 2–3 minutes per side until lightly browned.
Work in batches if needed. Transfer browned meatballs to a plate.
Simmer in sauce: Lower heat to medium-low. Pour the marinara into the skillet, scraping up browned bits.
Nestle the meatballs into the sauce. Cover and simmer 12–15 minutes, turning once, until cooked through (internal temp 165°F/74°C).
Finish and serve: Taste the sauce and adjust salt and pepper. Top with fresh basil and extra Parmesan.
Serve over zucchini noodles, roasted spaghetti squash, or with a side salad.