- Line a standard loaf tin with plastic wrap. Place butter and chocolate in a heatproof bowl and melt over a saucepan of simmering water, or microwave for 2 minutes to melt.
- Stir until smooth then set aside to cool for 10 minutes.
- Place egg yolks and icing sugar in a bowl and beat until pale and creamy. Stir this into the melted chocolate and butter. Whisk in whipped cream to combine.
- Pour the mixture into prepared tin and refrigerate overnight to set. Serve cut in slices.