Divide the mango between 2 ramekins. Mix together the passion fruit flesh, yogurt, crème fraîche, icing sugar and vanilla extract in a bowl, then spoon the mixture over the mango. Tap each ramekin to level the surface.
Sprinkle over the demerara sugar, then place the brûlées under a preheated hot grill and cook for 1–2 minutes until the sugar has melted. Leave to cool, then chill for about 30 minutes before serving.