For the layer, beat the eggs and sugar well, add flour, baking powder and grated lemon rind.
To prepare the cream, mix all products in a pot. Put it on low heat to thicken while stirring. Puree 1 banana and mix it into the cream.
Smear the baked cake layer with cream in the middle and put the whole peeled bananas in. Wrap up the roll the standard way and put it in a refrigerator for 2 hours.
Then brush the top with the remaining cream.