Beat the egg and water in a small bowl with a fork.
In a medium bowl, beat together the cream cheese and 1/4 cup brown sugar.
In a large bowl, stir the peaches, 1/4 cup brown sugar, flour, pecans, and vanilla extract together.
Unfold the pastry sheet on a lightly floured surface or onto a piece of parchment paper. Roll the pastry sheet into a 14x12" rectangle. (Cut in half lengthwise to make two smaller, or leave as is for one large strudel.)
Spread the cream cheese mixture onto pastry sheet, leaving 1 inch at edge of pastry. Spoon the peach mixture over the cream cheese.
Carefully roll the dough over the filling and roll up, pinching the ends of the dough together and gently tucking underneath the pastry roll.
Place the pastry onto a parchment lined baking sheet. Cut slits 1-inch apart on the top of the pastry with a sharp knife. Brush pastry lightly with egg wash and sprinkle with sugar.
Bake for 25 minutes or until the pasty is golden brown.
Let the pastry cool on the baking sheet on a wire rack for 20 minutes.
Serve with vanilla ice cream, or whipped cream, if desired.
Notes
You may use frozen instead of fresh peaches, if desired, 16 ounces frozen peach slices, thawed and well drained. This recipe makes 1 large strudel or 2 smaller ones.