Preheat oven to 180 degrees. Grease and flour a loaf pan.
Mash the bananas well and whisk along with the olive oil till smooth. Now add the sugar, vanilla and milk and whisk well.
Seive the dry ingredients over the wet ingredients and fold in till all moist.
Fold in most of the walnuts. Pour into the pan and top with the remaining walnuts.
Bake for around 60 minutes or till the skewer comes out clean.
Cool in the pan for 10 minutes, then flip onto the cooling rack and cool completely.