Make a sponge dough with eggs, sugar and flour and bake in a pan (approx. 30 x 20) at 180 °C for 15-20 minutes.
Make a pudding from custard powder and milk and let cool. Stir regularly so that a skin does not form.
Cream butter with sugar and fold into the cold pudding.
Slice bananas and place on sponge cake base, spread custard on top.
Prepare the chocolate icing according to package instructions and cover the banana slices with it.