In a glass measure, heat milk in microwave on Medium until hot and steaming, about 3 minutes or in small saucepan on stove top.
In medium saucepan, whisk together egg yolks, maple syrup and flour until well blended. Whisking constantly, in a steady stream slowly add hot milk. Cook over medium-low heat; whisking constantly, until starting to thicken, about 5 to 7 minutes. Reduce heat to low and cook 1 minute, whisking constantly.
Transfer to bowl; stir in butter, 1 tsp (5 mL) of the vanilla and lemon rind. Place plastic wrap directly on surface; refrigerate until chilled, 2 hours or up to 1 day.
Meanwhile, dust work surface lightly with flour. Cut pastry in half at perforation and roll each into 12 x 5-inch (30 x 12.5 cm) rectangle; trim edges to straighten. Cut each crosswise into 4 rectangles; with fork pierce each several times. Place on large parchment paper-lined baking sheet; refrigerate 15 minutes.
Bake at 425°F (220°C) until puffed and golden, about 13 minutes. Transfer to wire rack to cool.
In medium bowl, combine strawberries with remaining vanilla. Place pastry on serving plates; spread with jam, dividing equally. Spread custard over jam and top with strawberries, dividing equally. Drizzle with chocolate sauce and dust with icing sugar. Serve immediately.