Place the mango in a food processor and blend to a purée. Place the yogurt in a large bowl and add the agave nectar, to taste. Scape in the seeds from the vanilla pod and beat together until well combined.
Gently fold the mango purée into the yogurt mixture and divide between 4 glasses. Scoop the seeds from the passion fruit over the mango yogurt and serve immediately with crisp biscuits.