Mix the base: In a large bowl, combine ground turkey, Greek yogurt, egg, breadcrumbs, Parmesan, 2 minced garlic cloves, parsley, onion powder, oregano, red pepper flakes, salt, and pepper. Stir gently with a fork or your hands until just combined.
Do not overmix.
Shape the meatballs: Use a tablespoon or small scoop to form 18–22 meatballs, about 1.5 inches in diameter. Lightly oil your hands to prevent sticking.
Brown in batches: Heat olive oil in a large skillet over medium heat. Add half the meatballs, leaving space between them.
Cook 3–4 minutes per side until well browned. Transfer to a plate and repeat with remaining meatballs.
Make the garlic butter sauce: Reduce heat to medium-low. Add butter to the skillet and let it melt, scraping up browned bits.
Stir in remaining 2 minced garlic cloves and cook 30 seconds until fragrant.
Deglaze and simmer: Pour in chicken broth (or wine) and lemon juice. Simmer 2–3 minutes to reduce slightly. Taste and season with salt and pepper.
Finish cooking: Return meatballs and any juices to the pan.
Spoon sauce over the top. Cover and simmer 5–7 minutes, or until the centers reach 165°F (74°C).
Add herbs and serve: Stir in parsley. Plate meatballs with extra sauce over pasta, rice, or greens.
Garnish with more parsley and a squeeze of lemon. Add Parmesan if you like.