Grease and line up the base of 20-23 cm springform cake tin.
Place the digestive biscuits into a plastic bag and crush with a rolling pin, until you have fine crumbs, but leave some chunkier bits too.
Place the butter in a medium saucepan and melt on a medium heat. Add crushed digestives, stir the mixture together and transfer into prepared cake tin. Press the crushed biscuits into the tin with a back of a spoon, until levelled, cover and chill in the fridge.
Meanwhile, using an electric mixer, mix together the mascarpone cheese and double cream with vanilla until it is smooth and has very soft peaks.
Place the chocolate in a heat-proof bowl and place on top of a pan of simmering water, stir until melted, and set aside for 5-10 minutes.
Take out the cheesecake base from the fridge. Spread a layer of white chocolate over it, then top it up with mixture of mascarpone and double cream. Place half of raspberries in a blender and blitz until runny, then pour through a sieve into a bowl, discarding the seeds. Pour any remaining white chocolate over the top of the cheesecake, drizzle with raspberry coulis and decorate with remaining raspberries.
This recipe works best if you allow your cheesecake to set in the fridge for at least 5 hours or overnight.This recipe can also be frozen without the raspberry decoration for up to a month.