Place the mango in a food processor or blender and blend to a purée.
Put the yogurt and agave nectar, according to taste, in a large bowl, scrape in the seeds from the vanilla pod and beat together. Gently fold in the mango purée and spoon into tall glasses or glass serving dishes.
Scoop the seeds from the passion fruit and spoon over the mango yogurt. Serve immediately with thin biscuits, if liked.