Lemon and blackberry cakes

4 Turn the speed to medium and add the eggs, one at a time, then the sour cream and lemon zest and beat until creamy. Turn the speed to low and add the flour mixture in three additions, alternating with the lemon juice and beginning and ending with the flour, beating until smooth with no lumps.

5 Divide the batter among the prepared bun cases. Bake for 20 min, then rotate the pans 180 degrees and bake for another 5 min, or until the edges are golden and the cupcakes spring back when lightly pressed. Let the cakes cool completely in the pans on wire racks.

6 For the buttercream, combine the blackberries, granulated sugar and lemon juice in a small saucepan over medium heat, smashing the berries to a purée. Bring to a boil and let bubble for 1 min. Remove from the heat and strain the mixture through a fine-mesh strainer. Discard the pulp, and let it cool completely before continuing.

7 Beat the butter and 300g of the icing sugar in a mixer bowl on medium speed. Add the salt and 3 tbsp of the berry purée, turn the speed to low, and slowly add the remaining 200g icing sugar. If the buttercream is too thick, thin it with a little milk. (You will have some berry purée left over; it makes a delicious drink when added to to sparkling water.)

8 Fill a pastry bag fitted with a fluted or star tip and pipe the buttercream around the tops of the cupcakes, then top with a fresh blackberry.

Recipes taken from Sweet and Tart by Carla Snyder (Chronicle Books, £12.99)