Serves: 12 cakes1) Preheat the oven to 180C/Gas 4. Line the cups of a 12-cup cupcake tin with paper baking cases.
2) In a medium bowl, whisk together the flour, baking powder, bicarbonate of soda and salt. In a large bowl, beat the sugar and butter together using an electric mixer until it looks creamy. Beat in the egg, vanilla essence and peach extract until the mixture is smooth.
3) Add half the flour mixture to the butter mixture and stir until almost combined. Add the buttermilk and peach puree and stir again until almost combined. Add the rest of the flour and stir until all the ingredients are mixed in.
4) Fill the paper cases with batter using a large ice cream scoop. Bake for 18 to 20 minutes, or until a cocktail stick inserted in the cake comes out clean. Cool for 10 minutes before removing from the pans. Place on a wire rack and cool completely.
5) To make the filling, place a small saucepan on the hob on a medium heat. Add the peach puree and sugar in and bring to slight boil. In a separate small bowl, mix the cornflour and 1 tbsp water until there are no lumps.
6) Add the cornflour mixture to the pan and keep on a medium-low heat for about 1 minute. Allow to cool completely before using to fill the cupcakes.
7) To make the icing, put the mascarpone, cream and icing sugar in a stand mixer with the paddle attachment and beat on medium speed until thick, 4 to 5 minutes.
8) Fill the cupcakes with the peach filling and then decorate with the mascarpone icing.