Preheat the oven to 200°C.
Roll the pastry to 8mm thick and cut into two 28cm x 10cm rectangles.
Dust pastry with icing sugar and bake on a tray for 15 minutes until golden.
Whisk double cream to soft peaks, then add vanilla and caster sugar and whisk to stiff peaks.
Blend raspberries and lemon juice into a purée, adding icing sugar to taste.
Sieve the sauce into a bowl.
Split pastry pieces widthways to create four layers.
Layer pastry with whipped cream and raspberries three times.
Top with a final pastry sheet, more raspberries, and icing sugar.
Slice into portions and serve in a pool of raspberry sauce.