In a bowl, cream together the room-warm butter and sugar until fluffy. Beat in eggs and beat until fluffy.
Mash bananas with a fork and pass through a sieve, if desired. Mix into the egg mixture.
Now mix the flour with baking powder, baking soda, vanilla sugar and a good pinch of salt. Stir in alternately with the walnuts and the milk. Add a dash of cognac to taste.
Butter a loaf pan well, pour in the mixture and bake in a preheated oven at about 170 °C for 50-60 minutes.
Remove banana bread, let cool and turn out.