Whisk the eggs and sugar in a warm water bath until the mixture is light, creamy and double in bulk.
Remove from the water bath and whisk until cold and thick.
Fold in the melted butter gently.
Place in a greased floured Genoese mould.
Bake in a moderately hot oven at 200 degrees for 30 min.
Cream the butter and icing sugar, add the coffee essence.
Spread the cream onto the Genoese.
Portion the cake and serve.