Slice the chocolate cake and place evenly at the bottom of the trifle dish.
Splash the Grand Marnier or Cointreau evenly over the cake.
Use a small sharp knife to remove the skin and as much pith as possible from the oranges.
Hold each orange over a bowl and extract orange segments ensuring no pith remains.
Place the orange segments over the chocolate cake base. Cover in clingfilm and place in the fridge while you make the custard.
To make the chocolate custard heat the single cream in a saucepan until it is nearly boiling and then remove immediately from the heat.
Place the egg yolks and sugar in a large mixing bowl and beat with the electric hand whisk until thick and pale in colour.
Pour in the warm cream and whisk thoroughly.
Clean the saucepan and put the custard mixture in it. Heat gently, stirring until the custard thickens. Once the custard coats the back of a wooden spoon remove from the heat.
Place the chopped chocolate in the hot custard. Stir in until it has melted. If the chocolate doesn’t completely melt into the custard return it to the hob and warm on a gentle heat until it does.
Remove from the heat and whisk thoroughly with the hand whisk until the chocolate custard is smooth.
Pour the custard over the oranges and chocolate cake and leave to cool for 10 minutes.
Cover the trifle bowl with clingfilm and place in the fridge for about 2 hours or until the custard is cold and set.
Place the double cream into a large mixing bowl and whisk to soft peaks. Spread over the chocolate custard.
Decorate with orange zest and finely grated chocolate. Alternatively, you could make tuiles of chocolate and use these for decoration.
Place in the fridge until needed.
