Method
Grease a shallow 8" square cake tin. Break the chocolate into pieces and put into a saucepan with the butter and condensed milk. Heat gently stirring to blend until all the chocolate and butter has melted and the mixture is smooth. Do not allow the mixture to boil. Take off the heat and beat in the vanilla essence, orange zest and liqueur. Continue to beat the mixture well for a few minutes until thickened. Pour into tin and smooth out. Chill for a couple of hours until firm. Cut into squares to serve.

Grate some fresh zest on top if serving immediately.

Added on 30 December 2008.