Preheat the oven to 175 ° C top / bottom heat (convection around 160 ° C).
Mash the bananas with a fork. Mix all other ingredients in a bowl with a spoon and stir in the bananas.
Pour the batter onto a baking sheet lined with baking paper or into a brownie pan and bake on the middle rack. The baking time is 20 minutes for the baking tray and 25 minutes for the brownie pan. Make a chopstick sample each time. When no more liquid batter sticks to the stick, the brownies are ready.
Let cool down a bit on the tray and enjoy warm with a scoop of vanilla ice cream, cold with whipped cream and fresh fruit or simply enjoy it pure.