Pre-heat oven to 180°C.
Roll out the puff pastry until quite thin and cut into rectangles about 15cms x 9cms. They will shrink while cooking.
Lay them on a baking tray and place another baking tray on top of them.to stop them rising too much.
Bake until golden and crisp and cool on a rack. When cool split the rectangle horizontally by sliding a knife between the layers and easing apart.
Combine the whipped cream, mascarpone and the icing sugar. Crush 100g of the raspberries with a fork and stir through the cream mixture.
To serve Spoon some raspberry cream onto a layer of pastry, add some raspberries and top with another layer of pastry. Repeat the cream and raspberry layer and finish with a pastry top. Dust with icing sugar.