Preheat oven to 180°C conventional.
In a large bowl, sift together the flour, baking powder, bicarb soda and salt. Add in the caster sugar and combine all dry ingredients.
In the bowl of a stand mixer, add the butter, banana, eggs and vanilla and beat on a medium speed for 2 minutes until the ingredients are blended and the mixture is smooth.
Combine wet and dry ingredients and stir gently — do not over mix.
Fill cupcake liners ⅔ full and place in the oven for 20-25 minutes to bake, until the cupcakes are lightly browned. Check your muffins by placing a toothpick in the centre of the cupcake and, if it comes out clean, they are ready.
Meanwhile, for the miso butter, place the softened butter and miso in a stand mixer with the paddle attachment and beat for 5 minutes until light in colour and fluffy.
Remove the butter from the bowl and place onto a sheet of baking paper, rolling into a log and securing the ends by twisting them. Place in the fridge and chill until required.
Serve warm with a slice of miso butter.
