Garlic Butter Turkey Meatballs

Name: Garlic Butter Turkey Meatballs
Ingredients: 1 lb. ground turkey; 1/2 c. panko bread crumbs; 1/4 c. freshly grated Parmesan, plus more for serving (optional); 1 medium onion, finely chopped; 1 large egg; 3 cloves garlic, minced; 1 tbsp. freshly chopped parsley, plus more for serving; 1 tbsp. finely chopped chives; 1 tbsp. milk; Kosher salt; Freshly ground black pepper; 1 tbsp. extra-virgin olive oil; 2 tbsp. butter; 1/4 c. low-sodium chicken broth (or water); Roasted spaghetti squash, for serving