Line a large baking tray with baking paper. Unroll the pastry and lay it on the baking tray. Use a small knife to score a 2cm border around the edge of the pastry. Brush the scored edge with the beaten egg and bake for 20 minutes or until the edges are golden and puffed.
Remove from the oven and within the scored edge gently press the pastry down. Set aside to cool completely.
To make the mascarpone cream, beat the mascarpone and icing sugar in a bowl until well combined and smooth. In a separate bowl, beat together the thickened cream and vanilla bean paste until stiff peaks form and then gently fold the cream mixture through the mascarpone mixture until just combined.
Top the pastry with the mascarpone cream and then top that with the berries and mint leaves. Serve immediately.