Begin by prepping all the ingredients for the meatballs. In a large bowl, combine the breadcrumbs with the milk and let them soak for 2 to 3 minutes until moistened. Add the finely chopped onion, pressed garlic, chopped fresh sage, parsley, Italian seasoning, grated Parmesan, and the egg plus egg yolk. Using a fork, mix these ingredients until thoroughly combined. Then add the ground turkey, salt, and black pepper. Gently mix everything together with a light hand just until it comes together—don’t overmix, as the mixture will be quite sticky. This makes the meatballs more tender.
Using a 2-tablespoon scoop, portion out the meatball mixture and place the balls onto a parchment or wax paper-lined large platter. Place the formed meatballs in the freezer for 20 to 25 minutes. Chilling them helps them hold their shape during cooking. Once chilled, lightly wet your palms with water or a little oil, and gently roll each meatball between your palms to make them round.
Preheat a large heavy-bottomed skillet (cast iron or nonstick works well) over medium-high heat and add approximately 4 tablespoons of olive oil or avocado oil. Brush each meatball lightly with oil before placing them into the hot skillet. Sear the meatballs, then reduce the heat to medium or medium-low and continue frying, turning to brown on all sides. Cook for about 10 minutes, until they reach an internal temperature of 165°F. Transfer cooked meatballs to a clean platter and repeat with any remaining meat.
Wipe out the skillet used for frying the meatballs. Melt the ghee (or butter) and 1 tablespoon of olive oil over medium heat. Add the finely chopped onion and sauté for 2 to 3 minutes until softened. Next, stir in the pressed garlic and Italian seasoning; cook briefly until aromatic. Whisk in the pumpkin puree (both the can and the extra cup), salt, black pepper, and chicken stock, stirring until smooth. Allow the sauce to very gently simmer for 2 to 3 minutes to let the flavors meld. Off the heat, whisk in grated Parmesan, heavy cream, maple syrup, and chopped fresh sage. I personally like to add a splash more chicken stock if I want the sauce a little looser.
Add the cooked turkey meatballs (from Step 3) into the pan of pumpkin sage sauce (from Step 4). Allow them to sit and warm through in the sauce for a few minutes, letting the flavors soak in. If desired, garnish with fried sage leaves for a beautiful finish. Serve the turkey meatballs with the pumpkin sage sauce over your favorite pasta, gnocchi, or mashed potatoes. For a pop of color and crunch, I like to serve with extra fried sage leaves on top.