Preheat the oven to 350°F/180°C. Grease or line an 8.5×4.5-inch loaf pan with parchment paper
In a small dry pan, toast the walnut pieces over medium heat for 3-5 minutes until lightly toasted. Set aside to cool.
In small bowl, whisk the flour, salt, cinnamon and baking soda. Set aside.
Mash the bananas with a fork in a large mixing bowl. Add in melted butter, brown sugar, eggs, yoghurt and vanilla. Whisk it well until combined.
Tip in the dry ingredients and fold it together with a rubber spatula until combined.
Fold through the raisins and toasted walnuts.
Spoon the mixture into the prepared loaf pan. Sprinkle the top with a little coarse sugar.
Bake in the oven for approximately 50-60 minutes until the top of the bread springs back when touched and a skewer inserted into the center of the loaf comes out clean.
Remove the bread from the pan and let it cool on a wire rack for 20 minutes before slicing.