Using an electric whisk, beat the cream to soft peaks, then fold in the vanilla extract and chopped preserved ginger.
Arrange about 5-6 biscuits (depending on their size) in a circle on a serving plate, then fill the gap in the centre with more biscuits. Spoon a layer of the whipped cream in blobs onto each biscuit and dot over some raspberries, pushing them into the cream. Add another, smaller circle of biscuits in a layer, and add more cream and raspberries. Repeat until you have used all the cream and biscuits, then decorate with any remaining raspberries.
Put the cake in the fridge to chill for at least 3 hrs. To test if the cake is ready to serve, poke a skewer into the biscuits in the centre. Once they’re soft enough to cut, the cake is ready. Drizzle over some ginger syrup just before serving, if you like.
Flavour combinationsThis method suits all kinds of flavour combinations; try peanut biscuits with strawberries, or chocolate or caramel biscuits with layers of chocolate sauce and cream.