Preheat the oven to 180C.
Grease the inside of a loaf pan and line the bottom with parchment paper, grease and set aside.
Mix all the dry ingredients in a small bowl except the sugar.
In a large bowl beat the butter and sugar well, until pale and fluffy. Scrape the mixture down from the sides of the bowl.
Bring Together the wet ingredients – mashed banana, beaten eggs, yoghurt, and vanilla into the butter mixture and mix well to combine all the ingredients. The result should be a thick knobbly mixture.
Gradually add the flour mix to the batter, continually mixing and scraping the bowl, incorporating all the ingredients. Pour batter into prepared loaf pan and cook for 40 minutes or until an inserted skewer into the middle of the loaf comes clean.
Allow the loaf to cool in pan for 20 minutes then remove from pan, discard the parchment paper, and continue to completely cool on a rack. Cut thick slices and serve.