Heat the oven to 200C/180C fan/gas 4. Line a baking sheet with baking parchment. To make the crunch, put the flour in a bowl with the ginger and a pinch of salt and rub in the butter until you have a breadcrumb consistency. Mix in the sugar, pecans and pumpkin seeds. Throw in a splash of water and clump some of the mixture together using your fingers (this will make lovely crispy chunks). Tip the mix onto the baking sheet and bake for 15-20 mins until golden and crunchy. Remove from the oven, allow to cool slightly, then break it up. You can do this stage a few hours ahead of time.
Slice the peaches in half and remove (but keep) the stones. Slice open the vanilla pod and put the seeds in a pan with the sherry, butter, maple syrup and peach stones (they add a lovely almond note), along with the vanilla pods. Gently heat up, stirring, until the butter has melted and the mixture is gently simmering. Add the peach halves and poach for 20-30 mins until tender. Serve the peaches in little bowls with a splash of the poaching liquor, a dollop of natural yogurt and some of the crunch on top.