Frozen chocolate mousse

Method

• Step 1
  Lightly grease two 3/4-cup capacity ramekins or moulds. Line base and sides with a piece of plastic wrap. Allow plenty of overhang.
• Step 2
  Place chocolate and butter in a heatproof, microwave-safe bowl. Microwave, uncovered, on MEDIUM (50%) for 2 to 3 minutes, stirring every minute with a metal spoon, or until melted and smooth. Allow to cool for 5 minutes.
• Step 3
  Add liqueur and egg yolks to chocolate mixture. Stir until well combined.
• Step 4
  Using an electric mixer, beat eggwhites and salt in a small bowl until soft peaks form. Add sugar and beat well. Stir a third of eggwhite into chocolate mixture. Gently fold remaining eggwhite into chocolate mixture. Spoon into prepared ramekins. Fold over excess plastic wrap to cover. Freeze for at least 3 hours or overnight, if time permits, until firm.
• Step 5
  Using the plastic wrap, gently ease mousse from ramekins. Turn out onto chilled serving plates. Dust with cocoa and serve.