Beat the eggs and sugar in a bowl until thick and mousse-like (when the beater is lifted, a trail should remain on the mixture's surface for 10-15 seconds).

Gently fold in the flour mixture with a metal spoon, being careful not to knock out any air. Turn out the mixture into the prepared pan. Bake the sponge for 30-35 minutes, or until it springs back when lightly pressed. Turn out onto a wire rack and let cool completely.

Make the filling. Mix the soft cheese with the honey in a bowl. Beat until smooth, then stir in the Tia Maria and the chopped stem ginger.

Split the cake in half and sandwich the two halves with the Tia Maria filling.

Make the icing. Mix the confectioners' sugar and coffee extract with enough of the water to make an icing that will coat the back of a wood spoon. Spread three-quarters of the icing over the cake. Stir the cocoa into the remaining icing until smooth. Spoon into a piping bag fitted with a writing nozzle and pepper the mocha icing over the coffee icing. Decorate with coffee beans, if you like.