• 100g/4oz plain flour
• 40g/1½oz cocoa powder
• ½ tsp baking powder
• ½ tsp baking soda
• 100g/4oz caster sugar
• 50g/2oz brown sugar
• 2 large eggs, at room temperature
• 1 tsp vanilla extract
• 115g/4¼oz unsalted butter, melted
• 120ml/4½fl oz buttermilk
For the mint buttercream
• 200g/7oz unsalted butter, at room temperature
• 450g/1lb icing sugar
• 1-3 tbsp milk
• ½ tsp peppermint extract
• Green food colouring
• Shamrock chocolates, to decorate
1. Preheat the oven to 180°C, 350°F, Gas 4 and line a 12-hole cupcake tray with paper cases - green if you have them.
2. Sieve the flour, cocoa powder, baking powder and baking soda together in a mixing bowl, then add both sugars.
3. In a separate bowl, mix the eggs, vanilla and melted butter and whisk. Pour the wet ingredients into the dry, then whisk in the buttermilk until combined. Do not over mix.
4. Using an ice-cream scoop, drop equal amounts of the mix into each cupcake case, then cook in the preheated oven for 18-20 minutes until a toothpick inserted in the centre comes out clean. Remove from the oven and leave to cool completely on a wire rack.
5. While the cupcakes are cooling, make the mint buttercream. Beat the butter in a stand mixer or in a bowl using a hand-held mixer until light and fluffy, then add the icing sugar, a large spoonful at a time, until fully combined. Add 1-3 tbsp of milk until you have the desired consistency. Add the peppermint extract followed by the food colouring until you have your desired shade of green.
6. Fit a piping bag with a star nozzle and fill with the icing. Pipe a swirl of the buttercream onto each cupcake and top with a shamrock chocolate.