Fold the mascarpone, double cream, sugar, and vanilla seeds together and chill in a piping bag for 30 to 60 minutes.
Preheat the oven to 200°C and mix the butter with the egg whites.
Layer four sheets of filo pastry on a greased tray, brushing each layer with the butter and egg mixture.
Repeat the layering process for the remaining four sheets to create a second stack.
Bake the pastry stacks for 2-3 minutes until golden-brown and then let them cool.
Cut 12 discs from the pastry, sprinkle with sugar, bake for 2-3 minutes to melt, then top with pistachios.
Blend raspberries, strawberries, and sugar until smooth, then strain through a sieve to create the coulis.
Assemble by layering pastry discs with cream and strawberries, finishing with a pastry disc and a drizzle of coulis.