Best chocolate cupcake

Preheat oven to 180°C fan-forced. Line holes of two 12-hole 1/3 cup capacity muffin pans with paper cases. 

Put butter, vanilla and sugar in the bowl of an electric mixer and beat on high, using paddle attachment, until pale and fluffy. Add eggs, one at a time, beating well after each addition. Gently fold in sour cream, flour, cocoa and dark chocolate in 2 batches until combined.

Evenly spoon mixture (about 2 Tbsp per paper case) into prepared cases. Bake for 15 minutes or until lightly browned and when tested with a skewer, swapping position of tins in oven halfway.

Cool in tins for 5 minutes, then transfer cakes to a wire rack to cool completely.

To make chocolate buttercream icing. Put butter in the bowl of an electric mixer and beat on medium, using paddle attachment, until pale and fluffy. Mix the baking cocoa with the milk to form a smooth paste, then add this to the butter mixture. Finally, add your melted dark chocolate melts and remaining icing sugar to the mix and beat until fluffy.

Fit a piping bag with a 1cm star nozzle and fill with icing. Hold bag in an upright position and put nozzle at cupcake edge. Squeezing, pipe around edge, then spiral inwards, layering rings of icing. Repeat with remaining cupcakes and chocolate icing.

Decorate tops of cupcakes with cachous and chocolate curls.