Crush the biscuits into fine crumbs. Melt the butter and mix together. Spread the biscuit crumbs up the sides and base of the tart tin.
Flatten out with a spoon and use the bottom of a glass to compress the crumbs together. Chill in the fridge.
Cut the chocolate into small pieces, place into a bowl and add the liquid glucose. Place 300mls double cream into a saucepan and heat until just about to boil. Pour the cream over the chocolate. Allow to stand for 1 minute then whisk until smooth.
Add the chocolate filling on top of the biscuit base. Leave in the fridge for a few hours to set.
Pour 125mls double cream into a bowl. Add the sugar, vanilla bean paste and orange zest. Whisk until soft peaks form.
Fill a piping bag fitted with a plain nozzle and pipe cream around the tart then decorate with giant chocolate stars.