Preheat oven to 375°F. Mix 3 tablespoons of the sugar and cinnamon in small bowl. Beat egg and water in another small bowl. Set aside.
Sprinkle work surface with 1/2 cup of the remaining sugar. Coat puff pastry sheets on both sides with remaining 1/2 cup sugar. Roll out each sheet into a 13x12-inch rectangle. Fold one long side in thirds to the middle of the sheet. Repeat with opposite side. Fold sheet lengthwise in half. Dough should now be a 13x2-inch log with 6 layers. Repeat with remaining puff pastry sheet.
Cut logs into 1/2-inch thick slices. Place about 2 inches apart on ungreased baking sheets. Brush each slice with egg wash then sprinkle with cinnamon sugar. Keep uncut puff pastry log in refrigerator until ready to slice.
Bake 20 to 24 minutes or golden brown, turning palmiers over halfway through cooking. Remove to wire racks; cool completely.