Preheat the oven to 200°C and line two 12-hole cupcake tins with paper cases.
Beat the butter, sugar, flour, baking powder and salt in a bowl with an electric whisk.
Whisk the milk, vanilla and eggs in a jug.
Gradually add the milk mixture to the dry ingredients and beat until smooth.
Stir the mashed bananas into the batter.
Fill the cases and place one brazil nut into the center of each cupcake.
Bake for 20 minutes until the sponges spring back when pressed.
Cool the cupcakes in the tin briefly then transfer them to a wire rack.
Roll out and cut the skin-toned icing into circles to cover the cupcake tops.
Roll out and cut the black fondant to create hair shapes for the geishas.
Draw facial features with an edible ink pen and attach the hair using water or glue.