Peel and destone the mango, cutting the flesh into chunks, then add to a jug. Halve the passion fruit, scoop the seeds and pulp into the jug, then pour in the coconut milk. Blitz to a pulp using the multi-purpose blade – you may need to do this in batches. Stir through the chia seeds, then finely grate over the lime zest and squeeze in the juice. Divide the mixture between 4 glasses or jars, cover and leave in the fridge overnight.
Place a large frying pan over a medium heat. Roughly chop the nuts and add to the pan along with the seeds and oats. Toast for a few minutes, or until golden. Tip into a bowl, drizzle over the honey, then mix to coat. Allow to cool, then cover and leave overnight.
In the morning, place the frozen berries in the jug, tear in the bread and add half the yoghurt. Blitz until it reaches a rough ice-cream texture – you may need to do this in batches. Take the glasses or jars out of the fridge and divide the berry mixture between each. Finish each sundae with a dollop of yoghurt, then sprinkle over the sticky oat mixture and top with fresh fruit.