Combine Meatball Ingredients: In a large bowl, gently combine the ground turkey, panko breadcrumbs, Parmesan cheese, egg, chopped onion, minced garlic, chopped sage, dried thyme, salt, and pepper. Don't overmix.

Form Meatballs: Form the mixture into 1.5-inch meatballs. Wet hands slightly to prevent sticking. Place on parchment-lined baking sheet.

Brown Meatballs: Heat olive oil in a large skillet over medium heat. Brown meatballs on all sides, about 2-3 minutes per side. Remove from skillet and set aside.

Sautu00e9 Aromatics: In the same skillet, heat olive oil over medium heat. Add chopped onion and cook until softened, about 5-7 minutes. Add minced garlic and cook for another minute, until fragrant.

Incorporate Pumpkin Puree: Stir in the pumpkin puree, chicken broth, heavy cream, Parmesan cheese, chopped sage, dried thyme, and nutmeg. Whisk until smooth.

Simmer Sauce: Bring the sauce to a simmer, then reduce heat to low and simmer for 10-15 minutes, stirring occasionally.

Season Sauce: Season the sauce with salt and pepper to taste.

Add Meatballs to Sauce: Gently add the browned meatballs to the pumpkin sage sauce.

Simmer Together: Cover the skillet and let the meatballs simmer in the sauce for 15-20 minutes, or until cooked through (internal temperature of 165u00b0F/74u00b0C) and the sauce has thickened. Stir occasionally.

Serve: Serve over pasta, mashed potatoes, or polenta. Garnish with fresh sage leaves, grated Parmesan cheese, and/or red pepper flakes.