Nan keeps surprising me with these measurements. Weigh your eggs first, I guess!

Cut sponge cake into large chunks and soak in sherry.

Separately, beat together eggs, butter and sugar until smooth and glossy. Add coffee essence.

Line a bowl with wax paper. Arrange pieces of soaked sponge cake in bowl, reserving some to cover the top.

Pour butter mixture over and place remaining sponge on top.

Refrigerate 24 hours.

Remove from bowl and decorate with whipped cream to serve.