Preheat oven to 350. Brown turkey and drain. Prepare instant mashed potatoes as instructed on the box (minus the butter). Set aside. Spray Pam into an 8x8 casserole dish. Pour the stuffing in the bottom. Mix in 1/8 c of water until moist. Crumble turkey on top. Pour gravy over turkey layer. Spread potatoes over gravy. Cut butter into pieces and place on top of the potatoes. Bake for 30 minutes at 350.