To make the blueberry compote, combine all of the ingredients in a small saucepan and cook over low heat for 3–5 minutes, or until softened and syrupy. Remove from the heat and set aside to cool.

To make the mousse, melt the chocolate in a heatproof bowl set over a saucepan of almost simmering water. Set aside to cool slightly.

Whisk the egg yolks and sugar together, until pale and creamy. Gradually pour in the melted chocolate, stirring constantly to combine.

Whisk the cream and egg whites in separate bowls, using an electric mixer fitted with a whisk attachment, until soft peaks form.

Gently fold the cream and then the whites through the chocolate mixture.

To serve, spoon the compote into the base of four small serving glasses, top with mousse and a few fresh blueberries to decorate. Refrigerate for at least 2 hours, or overnight to set.