Preheat the oven to 190°C/375°F/Gas Mark 5. Line a muffin tray with 10 paper muffin cases.
Place the sugar, butter, eggs, flour, baking powder and milk in a large bowl and mix with an electric whisk until pale and creamy.
Divide the mixture between the muffin cases and bake for 15-20 mins until risen, golden and firm to the touch. Transfer to a cooling rack. Leave to cool.
To make the buttercream, place the butter in a bowl and sift over the icing sugar. Beat until smooth.
Slice the tops off each cake and fill the cavities with a little buttercream and jam. Cut each sliced top in half and arrange on top of the filling to resemble butterfly wings. Dust lightly with icing sugar.
Nutritional information per portion
This nutritional information is only a guide and is based on 2,000 calories per day. For more information on eating a healthy diet, please visit the Food Standards Agency website.
Guideline Daily Amount for 2,000 calories per day are: 70g fat, 20g saturated fat, 90g sugar, 6g salt.