For the nut-banana bread, cream the butter and margarine until very fluffy, gradually beat in the sugar and eggs.
Peel the bananas and mash them finely with a fork. Mix with lemon juice. Mix the flour with the baking powder and the chopped walnuts.
Grease a loaf pan and dust with flour. Stir the mashed bananas into the dregs. Mix the vanilla sugar with the milk and stir into the banana batter alternately with the flour.
Finally, season the dough with a pinch of salt, pour it into the loaf pan and bake in the preheated oven at 170°C for 50-60 minutes.
After cooling, slice the nut-banana bread.