Preheat oven to 350°F. Spray a 2-quart casserole dish with nonstick cooking spray and spread prepared mashed potatoes in the bottom.

Combine turkey and gravy in large skillet and bring to a simmer, stirring occasionally. Remove from heat and stir in stuffing until thoroughly combined. Add salt and pepper to taste, if desired. Spoon turkey mixture on top of potatoes and spread evenly.

Cover and bake 25 to 30 minutes, or until heated through.