1.Place berries in medium bowl; sprinkle with liqueur and 1 tablespoon of the icing sugar.
2.Preheat oven to 220°C/425°F. Line oven tray with baking paper (parchment).
3.Cut pastry sheet into 8 rectangles. Place on oven tray. Dust pastry with 2 teaspoons of the sifted icing sugar. Bake about 10 minutes. Cool.
4.Beat mascarpone, cream and 2 tablespoons of the remaining sifted icing sugar in small bowl with electric mixer until soft peaks form.
5.Sandwich mascarpone mixture, berries and any berry juices between pastry slices. Dust matchsticks with remaining sifted icing sugar.