In a microwave (20 secs at a time) or over a double-boiler, gently melt the chocolate, stirring until smooth. Set this to one side to allow it to cool to room temperature.
Whip the cold cream for several minutes, using an electric mixer or stand mixer, until it forms soft peaks.
In a separate bowl, beat the cream cheese, sugar, orange extract and orange zest until smooth and fluffy.
Beat the melted chocolate in to cream cheese mix until combined.
Gently fold the whipped cream into the chocolate mix until smooth (i.e. white streaks have disappeared).
Spread the filling evenly over the chilled base, smoothing gently, then cover with cling film and refrigerate for at least 3hrs or overnight to set.
Once set (firm to the touch), remove your cheesecake from the tin, decorate and then enjoy!