Preheat oven to 350°F. Lightly coat a 3-quart baking dish with cooking spray.

Cook penne according to package directions. 

In a large bowl, add cooked penne, pumpkin puree, heavy cream, 2 cups mozzarella, sage, salt, and garlic powder; stir to combine. 

Transfer mixture to baking dish and sprinkle with remaining 1 cup mozzarella. 

Bake at 350°F for 15 to 20 minutes, until cheese is bubbly and melted. Cool slightly before serving.