White Chocolate & Orange Marscapone Cheesecake

For the biscuit base:75g/3oz butter,melted
225g/8oz bourbon biscuits, crushed
For the filling:
225g/8oz marscapone cheese
2eggs separated
50g/2oz caster sugar
150ml/ 1/4pint single cream
4 Tbsp Cointreau
15g/ 1/2oz sachet gelatine
75g/3oz white chocolate
crystallised orange segments to decorate
icing sugar & cocoa powder to dust

For the biscuit base:
Grease & base-line a 20cm/ 8in round spring-form cake tin.Mix the butter & biscuit crumbs together & press into the base.Leave to set in a cool place.
For the filling:
1.Beat the cheese in a bowel until softened slightly,then beat in the egg yolks,sugar & cream.
2.Place the Cointreau in a bowel & sprinkle the gelatine over.Stand for 2mins,then dissolve over a pan of simmering water.Remove from heat.
3.Melt the chocolate in a bowel over a pan of simmering water.Remove from the heat.Stir the gelatine & melted chocolate into the cheese mixture.Whisk the egg whites until stiff & gradually fold in.Pour over the biscuit base.Chill until set.
4.Decorate with crystallised orange segments & dust with icing & cocoa powder