In a container, mix the yoghurt, sugar and vanillas and stir well. You can use brown sugar or white but it turns out tastier with brown because it gives the cake its typical light caramel aroma.
Pour enough of the mixture at the bottom of a rectangular glass cooking container to cover it. You can use any rectangular bowl or tray though.
Next, arrange a layer of biscotti, pour on mixture, then another layer of biscotti and put mixture again on top.
At the very top, arrange round slices of bananas and sprinkle with sugar sprinkles. Cover the container with foil and put it in the fridge.
The Cake with Biscotti, Bananas and Yoghurt needs to sit for 2-3 hours in the fridge for the biscotti to take in yoghurt and soften.