Preheat the oven to 180ºC/160ºC Fan/ Gas 4/350ºF. Line a cupcake tray with 12 cupcake cases.

Add the flour, cocoa powder, caster sugar, baking powder, salt and butter to a large mixing bowl. Use a handheld electric whisk to beat the ingredients together until they are the consistency of sand. Add the orange zest and thoroughly mix it in.

In a separate bowl add the orange juice, milk and eggs and whisk together.

Pour half of the wet ingredients into the dry ingredients and beat well. Pour the remaining wet ingredients into the mixing bowl and beat for a couple of minutes until the mixture is fully combined and smooth.

Divide the cupcake batter between the 12 cupcake cases. Bake in the centre of the oven for 20-25 minutes or until the sponge bounces back when touched.

To make the buttercream chop chocolate orange into small pieces and put it into a heatproof bowl set over a pan of simmering water to melt it. When it has melted set aside to cool.

Put the softened butter into a mixing bowl and beat it with a handheld electric whisk until creamy. Add the icing sugar and beat until the mixture is the consistency of sand. Add the cocoa powder and (cooled) melted chocolate orange and beat again. The mixture will look like lumpy sand. Add the milk and continue to beat until the buttercream becomes smooth and fluffy. You can add a little more milk if it looks too thick.

Transfer the buttercream to a piping bag fitted with a piping nozzle. When the cupcakes are completely cool, cut a hole out and spoon a small amount of Tangy Orange Curd into the cupcake and then pipe swirls of buttercream on top and decorate with freshly grated orange zest.