For the filling, break the chocolate into small pieces and place in a heatproof bowl. Make a bain-marie (put the bowl over a saucepan of simmering water) and allow the chocolate to melt. Heat the cream in a small saucepan and add it to the melted chocolate, mixing until evenly blended. Leave to cool for 2 hours. Then, using an electric whisk, beat until the mixture becomes stiff and holds its shape.

Line 3 baking trays with baking parchment. Put the filling mixture into a piping bag with a 1cm plain nozzle and pipe little mounds — or nipples — on to the baking parchment. Put in the fridge to chill and set.

Melt the dark chocolate in a bain-marie. Take each chilled nipple and dip in the melted dark chocolate. Return to the parchment paper and leave to set for an hour.

Melt the white chocolate in a bain-marie. Take each dark-chocolate-covered nipple and dip the tip into the white chocolate. Leave to set.