For the pastry, place the pastry onto a board and cut out four 10cm/4in discs. Place onto a non-stick baking sheet and leave to rest in the fridge for a few minutes.
Dust the pastry heavily with icing sugar, then transfer to the oven and bake for 5-6 minutes, until golden-brown and crisp. Remove from the oven and allow to cool. Carefully cut each pastry disc into three across the middle to make a total of 12 thin discs.
For the raspberry sauce, place the raspberries, icing sugar and water into a blender and blend until smooth. Pass the mixture through a sieve to remove the pips.
For the filling, mix the mascarpone with icing sugar, to taste (optional), in a bowl. Place a pastry disc onto four serving plates and top each with a spoonful of the mascarpone mixture. Top with a few strawberries and place some raspberries around the edge of the mascarpone. Repeat the process with a second layer of pastry, mascarpone and fruit. Finish with the remaining pastry disc and top with a strawberry.
To serve, pour a little of the raspberry sauce around the puff pastry stack on each serving plate and garnish with mint.