To make the base, combine the crushed biscuits, melted butter and zest in a small bowl and mix to thoroughly combine. Press the biscuit mix into the bottom of an individual loose-bottom tart case and set aside while you prepare the filling.
Combine cream cheese, double cream, Baileys and icing sugar in a small bowl and whisk to smooth firm peaks. Top the biscuit base with the filling, smooth the top and chill for at least 1 hour to set.
To serve, remove the cheesecake from the tart case and top with whipped cream, some grated chocolate and a little orange zest.
