- In a saucepan, off the heat, combine sugar and cornstarch. Add the applesauce. Bring to a boil over medium heat, stirring constantly with a wooden spoon. Add the apple. Allow to cool. Cover and refrigerate for about 1 hour or until the filling is at room temperature.
- Line a 43 x 30-cm (17 X 12-inch) baking sheet with parchment paper.
- On a floured work surface, roll out the dough into two 35 x 15-cm (14 x 6-inch) rectangles. Place on the baking sheet. Cover and refrigerate for 30 minutes.
- With the rack in the middle position, preheat the oven to 200 °C (400 °F).
- On a work surface, cut a rectangle of dough into 12 strips of about 1 x 35-cm (1/2 X 14-inch), with a serrated pizza cutter or knife.
- Spread the apple filling on the pastry up to 2.5-cm (1-inch) of the rim. Brush the perimeter of the pastry with water.
- Place, diagonally, 6 strips of dough side by side, spacing them equally over the filling. Gently squeeze the strips around the perimeter. Repeat with remaining strips in the opposite direction.
- Brush the strips with melted butter. With the pizza cutter or knife, cut around the pastry to remove any excess dough. Sprinkle with the sugar.
- Bake for 30 minutes or until the pastry is golden brown.
- Serve warm or cold with crème fraîche or vanilla ice cream.
Add cinnamon to the filling, to taste.