Grease and line an oblong (13 x 9 inch/33 x 23 cm) tin with parchment paper.
In a mixing bowl beat the 4 eggs with the sugar for the sponge base. It should become very light and aerated. The whisk should leave a figure of eight pronounced on the surface of the mixture when the whisk is lifted out of it.
Gently fold in the sifted flour with a metal spoon. Be very gentle so as not to knock any of the generated air out of the sponge base but also ensure that all of the flour is incorporated. Pour the mixture into a prepared Swiss roll tin.
Bake for 20 minutes, until well risen and golden brown and take the sponge out of the oven.
Before the sponge is fully cooled, invert it onto a sheet of parchment paper dusted with the caster sugar (50g/2oz) and spread with a thin layer of apricot jam.
Carefully roll the Swiss roll up from the longest side rather than from the shortest.
Slice in thin slices and arrange in individual glasses or a large bowl making sure that the glass or bowl is fully lined all the way around. Retain a little of the sponge for the middle if you so desire.
Sprinkle with some freshly bananas, additional jam if desired, and a generous helping of sherry. Do a few layers of the sponge if you wish.
Make up the angel delight according to the packet and pour this over the sponge and banana mixture.
Transfer to the fridge to set and then decorate with dark chocolate shards.