Add the ground chicken, pumpkin purée, breadcrumbs, egg, garlic, onion powder, salt, and black pepper to a large mixing bowl.
Gently mix until the ingredients are evenly incorporated. Avoid overmixing, which can make the meatballs dense.
Lightly wet your hands and shape the mixture into approximately 1½-inch meatballs. You should have about 16 meatballs.
Heat the olive oil in a large skillet over medium heat.
Arrange the meatballs in the skillet without overcrowding the pan. Cook for approximately 2–3 minutes per side, turning carefully until evenly golden.
Continue cooking until the centers of the Pumpkin Chicken Meatballs reach a safe internal temperature of 165°F (74°C).
Meanwhile, melt the butter in a separate saucepan or clean skillet over medium-low heat.
Add the minced garlic and chopped fresh sage. Cook for approximately 30 seconds, stirring frequently, until fragrant.
Pour in the heavy cream and stir gently. Season with salt and black pepper to taste.
Bring the sauce to a gentle simmer and cook for 3–4 minutes, stirring occasionally. Avoid a rapid boil.
Transfer the cooked meatballs into the creamy sage sauce and gently turn them until evenly coated.
Simmer over low heat for another 5–7 minutes, allowing the sauce to thicken slightly and the flavors to come together.
Serve warm in shallow bowls with extra creamy sage sauce spooned over the meatballs. Garnish with fresh sage and freshly ground black pepper if desired.