1 Heat the oven to 190°C (180° fan) 375°F gas 5. Place paper cases in a 10 hole muffin tin.
2 Sift the flour, baking powder, bicarbonate of soda, salt and cinnamon into a mixing bowl. Stir in the sugar.
3 Beat together the eggs, vanilla oil and milk. Mash the bananas and stir into the mixture.
4 Make a well in the centre of the dry ingredients and add the egg mixture, stirring until just combined. The mixture will be lumpy.
5 Spoon into the paper cases and bake for 20-25 minutes until risen and golden. Cool in the tin for 5 minutes, then place on a wire rack to cool completely.
6 For the topping: beat the butter until soft, then sift in the icing sugar.
7 Gradually beat in the mascarpone and vanilla until smooth and creamy.
8 Spread on top of the cakes and decorate with blueberries.