In a large mixing bowl, combine the ground chicken, pumpkin purée, plain breadcrumbs, egg, grated garlic, onion powder, salt, and black pepper. Mix gently until just combined.

Using damp hands, roll the mixture into 1.5-inch balls, yielding about 16 meatballs.

In a nonstick skillet, heat olive oil over medium heat. Cook meatballs for 2–3 minutes on each side until golden brown.

In a separate saucepan, melt unsalted butter over medium-low heat. Add garlic and sage, sautéing until fragrant. Stir in heavy cream, salt, black pepper, and nutmeg.

Transfer browned meatballs to the sage cream sauce. Cover and let simmer for 5–7 minutes.

Serve meatballs and sauce in a shallow bowl. Garnish with extra chopped sage if desired.