The cupcakes have a muffin like texture to them - the topping is very sweet but is nicely counter balanced by the actual cake. I found this recipe in The Cupcake Book by Susanna Tee.
225g plain white flour
1 1/4 tsp baking powder
1/4 tsp bicarb of soda
2 ripe bananas, mashed
115g butter, softened
115g caster sugar
1/2 tsp vanilla extract
4 tbsp soured cream
55g walnut pieces, roughly chopped
175g butter, softened
350g icing sugar
some walnut pieces, roughly chopped
1. Preheat oven to 190C/375F/Gas Mark 5. Line a cupcake tine with 14 paper cups. Sift together the flour, baking powder and bicarb of soda.
2. Whisk the butter, caster sugar and vanilla extract together in a large bowl until light and fluffy. Gradually beat in the eggs, then stir in the mashed bananas, soured cream and walnuts. Fold in the flour mixture.
3. Put the mixture into the paper cups and bake for about 25 mins until risen and firm and golden brown. Leave to cool in the tin for about 10 mins before transferring to a wire rack to cool properly.
4. For the frosting, beat the butter until light and fluffy, then sift in the icing sugar and mix well together. I added a little bit of vanilla extract too.
5. Decorate the cupcakes when cool with the icing and chopped walnuts.