Prepare the meatball mixture. Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper. Add the ground chicken, pumpkin puree, breadcrumbs, Parmesan, egg, onion, garlic, sage, salt, black pepper, and garlic powder to a large bowl. Mix gently just until evenly combined.
Shape the meatballs. Divide the mixture into approximately 16 evenly sized meatballs using a cookie scoop or spoon. Arrange them on the prepared baking sheet with a little space between each one. Brush or drizzle the tops with olive oil.
Bake. Bake for 18–20 minutes, or until lightly browned and the centers reach an internal temperature of 165°F (74°C).
Prepare the sauce. While the meatballs bake, melt the butter in a large skillet over medium heat. Add the garlic and fresh sage and cook for about 1 minute, stirring frequently, until fragrant.
Make it creamy. Pour in the chicken broth and simmer for about 3 minutes. Add the heavy cream, Parmesan, and black pepper. Whisk until smooth, then gently simmer until the sauce begins to thicken.
Finish the dish. Transfer the baked pumpkin chicken meatballs to the skillet. Spoon the sage cream sauce over them and simmer gently for about 5 minutes, until everything is hot and the sauce coats the meatballs.
Serve. Serve warm with additional Parmesan and chopped fresh sage, if desired.
Notes
Ground turkey can be substituted for ground chicken if desired. You can also use dried sage when fresh sage is unavailable; start with a smaller amount because dried herbs have a more concentrated flavor.