Whoopie Pies

Preheat the oven to 170°C (150°C, 325°F, gas mark 3). Line 2 baking trays with baking paper.

Heat the milk gently in a small saucepan, add the sugar, then take the pan off the heat, add the soured cream and stir through to combine.

Leave to cool to body temperature. Meanwhile, put the flour, bicarbonate of soda, baking powder, cocoa and salt together in a large bowl.

Once the milk mixture has cooled to body temperature, add the eggs, vanilla and oil to the pan and stir to just combine. Pour the liquid ingredients into the flour mixture and fold gently together.

Transfer the mixture into a piping bag fitted with a large nozzle and pipe circles about 8cm (3") in diameter on to the lined baking trays, spaced about 8cm (3") apart. Bake in the oven for 8–10 minutes, or until a skewer inserted in the thickest part comes out clean.

Leave the whoopie cakes to cool on the trays. Meanwhile, to make the buttercream, beat the butter, icing sugar, and cocoa powder together in a bowl until light and fluffy, then beat in the milk.

Once the whoopies are completely cool, gently release them from the baking paper. Take a generous dollop of the buttercream and spread it onto the flat base of one of the whoopies, then sandwich it together with a second whoopie. Repeat with the rest of the cakes.

To make vanilla flavoured whoopies, omit the cocoa powder and add an extra 55g (2oz) of flour. For coffee flavours, omit the cocoa powder and add an extra 55g (2oz) of flour, plus a few drops of coffee essence or 2 tablespoons of instant coffee powder stirred into the warmed milk.