Break the dairy-free dark chocolate into pieces and melt it gently in a heatproof bowl over a pan of simmering water, or in short bursts in the microwave.
Leave the melted chocolate to cool slightly for 5 minutes.
In a separate bowl, whisk the chilled dairy-free cream until thickened and airy.
Stir the maple syrup and vanilla extract into the melted chocolate.
Gently fold the whipped dairy-free cream into the chocolate mixture until smooth and fully combined.
Spoon the mousse into serving glasses or ramekins.
Chill for at least 2 hours until set.
Serve topped with fresh berries or dairy-free chocolate shavings if liked.