1. Thaw pastry sheet at room temperature 30 minutes. Preheat oven to 400 degrees. Mix egg and water and set aside.
2. Unfold pastry on lightly floured surface. Roll into 16- by 12-inch rectangle. With short side facing you, layer ham and turkey on bottom half of pastry to within 1 inch of edges. Sprinkle meat with cheese. Starting at short side, roll up like a jelly roll. Place seam-side down on baking sheet. Tuck ends under to seal. Brush with egg mixture.
3. Bake 25 minutes or until golden. Slice and serve warm.