Preheat the oven to 180°C (350°F). Line a 22 cm (8.6 inch) long loaf tin with baking paper.
Add all the dry ingredients to a large mixing bowl. Mix until there are no lumps.
Add the banana and pineapple to a medium mixing bowl and use a stick blender to puree. Add the puree and the rest of the wet ingredients to the large mixing bowl and mix until combined. Pour the batter into the tin.
Bake the loaf in the oven for 40-50 minutes or until a skewer can be inserted into the middle and there is no wet batter on it. The cake is moist and there might be some crumbs on the skewer which is fine.
Allow the loaf to rest in the cake tin for at least 5 minutes. Remove it from the tin and allow it to cool on a wire rack.
To decorate (optional): Spread the coconut yoghurt on the loaf and arrange the blueberries on top. Slice and enjoy!
The cake can be kept without the frosting at room temperature for 1 day or in an airtight container in the fridge for 3 days. Without the frosting, you can freeze slices of the loaf for up to 1 month.