Melt the chocolate in a heatproof bowl set over a pot of barely simmering water, stirring until smooth, then set aside to cool for 5 minutes.

Whip 1 cup of the cream in a separate bowl until soft peaks form.

Fold the Baileys into the melted chocolate, then fold in the whipped cream in two additions, keeping the mixture light rather than stirring it flat.

Divide the mousse among 6 to 8 small glasses and chill for at least 2 hours, until fully set and no longer soft in the center.

Just before serving, whip the remaining 1 cup of cream with the powdered sugar until soft peaks form.

Spoon or pipe the whipped cream on top of each mousse cup.

Finish with a scatter of chocolate shavings.