Mix the sugar with the butter with a hand mixer until you have a creamy mixture for at least 3 minutes. Add the eggs one by one in medium speed add the bananas and the vanilla extract and the yogurt and mix well.
In another bowl add the dry ingredients and mix them and add them. Add the dry ingredients to the first mix, and mix it with a spoon by hand till the flour pockets are gone. Add the chopped walnuts; fold the nuts in the batter with the spoon.
Transfer the batter to the baking pan and cover it with aluminum foil for 40 min. This will prevent your banana bread to get too dark. After 40 minutes, take out the aluminum foil, and bake it for another 20 min.
To get a moister taste you can leave in the fridge for 2 days and it will get softer.