100g (3/4 cup) plain flour

40g (1/2 cup) cocoa powder (the best quality you can afford)

3/4 tsp baking powder

1/2 tsp bicarbonate of soda

2 eggs

100g (1/2 cup) caster sugar

100g (1/2 cup + 2tsp) light soft brown sugar

80ml (1/3 cup) vegetable oil

2 tsp vanilla extract

120ml (1/2 cup) milk (I used skimmed but I'm sure any milk would work well)

1 tsp lemon juice

Pinch of salt

50g (1/4 cup) dark chocolate (I used 55% cocoa solids)

100g (2/5 cup) butter, softened

200g (2 cups) icing sugar, sieved

1 tsp vanilla extract

Milk (to loosen the buttercream, you won't need more than a tbsp)

1-2 tbsp cocoa nibs, crushed (or chocolate sprinkles) (optional)

These chocolate cupcakes are easily my favourite cupcake! The sponge is deeply chocolatey and stays incredibly moist due to the use of oil in the batter (rather than butter). I had a couple left after a week (after baking these, my boyfriend decided to cut down on the sweet stuff, and I hadn't managed to eat them all myself!) and the sponges hadn't dried up at all!I topped the cupcakes with a chocolate buttercream - I'm normally not a huge fan of cocoa-based buttercreams as I don't find the flavour chocolatey enough for me. To make the perfect chocolate buttercream, therefore, I melted 50g of dark chocolate and added this to the buttercream. Wow, this is cupcake packs a chocolate-hit!! Just to make the cupcakes even better, I sprinkled the tops with some crushed cocoa nibs (but you could use chocolate sprinkles if you like).Makes 12For the cupcakes:For the chocolate buttercream:1. Preheat your oven to 180c/350f/gas mark 4. Line a 12 hole muffin tin with cupcake cases.2. Sift together the flour, cocoa, baking powder and bicarbonate of soda and set aside.3. In a separate bowl, whisk together the eggs, caster sugar, brown sugar, vanilla, milk, lemon juice and salt for a few minutes until smooth.4. Make a well in the centre of the flour mix and pour in the eggy mixture. Fold through until you have a very loose batter with no obvious lumps of flour.5. Use an ice cream scoop to spoon batter into the cases so that they are half filled. Do not overfill them as they will rise up a lot!6. Bake for around 20 minutes, until well risen, springy to the touch, and a skewer inserted into the centre comes out clean. Set aside to cool.7. To make the buttercream, chop the dark chocolate finely and place in a bowl over a pan of simmering water (being careful that the bowl does not actually touch the water). Stir occasionally until the chocolate has melted, then set aside to cool for a few minutes (until it is hand hot).8. Cream the butter against the sides of a mixing bowl until it is very soft and spreadable. Add half of the icing sugar and beat with a wooden spoon to dissolve the sugar. Add the other half of the icing sugar and melted dark chocolate and continue beating. It will be quite loose as the melted chocolate may melt some of the butter. Place in the fridge for 20 minutes to firm up to be able to be piped.9. When ready to assemble, place a 1M piping nozzle into a piping bag and fill with the buttercream. If the buttercream has become overly stiff, add a splash of milk and beat.10. Starting at the outside edge of a cupcake pipe a swirl towards the centre. This gives an ice-cream cone-like look that works well I think.11. Sprinkle with cocoa nibs or chocolate sprinkles to finish (optional).12. Enjoy!