Put the crème de cassis or cordial in a saucepan over a low heat and gently heat, then add the berries. Stir, cover and cook for about 5 minutes or until the fruit has thawed and is beginning to collapse. Remove from the heat and stir in between 1–3 tablespoons of the icing sugar, according to taste. Cool completely, then chill for at least 1 hour.
Mix together the fromage frais, yogurt and 1 tablespoon of the icing sugar in a bowl. Scrape in the seeds from the vanilla pod and beat to combine.
Fold the berries into the fromage frais mixture until just combined. Carefully spoon into decorative glasses or glass serving dishes and serve immediately, scattered with toasted almonds, if liked.