Preheat the oven to 375°F. Beat the egg and water in a small bowl with a fork. Set aside.

Stir granulated sugar and cinnamon in a medium bowl. Add the apples and stir to coat.

Sprinkle some additional flour on the work surface. Unfold the pastry sheet on the work . Roll the pastry sheet into approximately 16 x 12-inch rectangle. With the short side facing you, spoon the apple mixture onto the bottom half (closer to you) of the pastry sheet. Keep 1 inch of the edge clear without filling for pinching and sealing later. Roll up like a jelly roll. With seam-side down place on a baking sheet. Tuck both ends under to seal. Brush the pastry with the egg mixture. Cut several slits 2-3 inch cuts in the top of the pastry.

Toss cinnamon and sugar together in a small bowl. Sprinkle over dough. Bake for 35 minutes or until the pastry is golden brown. Let the pastry cool on the baking sheet on a wire rack for 20 minutes.