Set aside about 2/3 cup (150 ml) of the milk to beat with the flour. Put the rest of the milk with the sugar in a pot on the stove to boil. Add the butter, the flour beaten with the set aside milk and finally - the yolk and vanilla. Leave to cool slightly.
Cut the Swiss rolls and bananas into thin slices.
In a round bowl, the walls of which you've covered with plastic wrap, start arranging. Start from the center of the round bowl - the bottom, then cover its walls with Swiss roll slices as well.
Next, arrange a layer of cream, the sliced bananas and another layer of Swiss rolls, this time just along the bottom. Between every layer of rolls put a layer of cream and fruits, until out of ingredients.
Cover the bowl with plastic wrap and put it in the fridge. It's best to have it sit in it for a longer period of time, to harden well.