Melt the chocolate over a ban marie and set it to one side to cool.
Separate the egg and whisk the yolk with the sugar until slightly thick, then add in the melted chocolate.
Next whisk in the Irish cream, cream and coffee until the mixture has thickened.
Whisk the egg white to stiff peaks and carefully fold this into the chocolate mixture.
Spoon into white ramekins and place in the fridge for an hour or two to set.
To make the gingerbread, place the dry ingredients in a bowl along with the butter. Beat until the mixture is fluffy then add the egg, and the treacle.
Split the dough in two and roll it in between two pieces of parchment paper. Place in the fridge for 10-15m or until firm. Then using a small Christmas tree cookie cutter, cut shapes out and bake them at 180C until just golden around the edges.
To assemble, place a gingerbread tree in the top of the mousse, along with a few chocolate shavings. Add a light dusting of icing sugar. Place a round glass on top and dust more icing sugar over the glass.
