Heat oven to 425°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray.
Separate each can of dough into 10 biscuits; flatten each biscuit into thin round. On center of each round, place 1 teaspoon mashed potatoes, 1/2 teaspoon cranberry sauce and a few pieces of turkey. Fold edges up and over filling; pinch to seal. Place biscuits, seam sides down, in baking dish
In small bowl, beat egg and water. Lightly brush tops of biscuits with egg mixture.
Bake 15 to 20 minutes or until golden brown. Serve biscuits warm with gravy.