For the spiced peaches and plums: Melt the butter in a medium pot over medium heat. Add the cinnamon, star anise and vanilla bean. Pour in the apple juice, and bring to a boil. Add the peaches, plums and thyme. Gently poach until the fruit is soft and easily pierced with a knife, 15 to 20 minutes.
Meanwhile, preheat the oven to 400 degrees F.
For the crumble topping: In a food processor or mini chopper, pulse the butter, brown sugar, almond flour, oats, pistachios and cinnamon to the consistency of rough breadcrumbs.
Remove the fruit with a slotted spoon, reserving the syrup, and lay in a shallow oven-proof baking dish. Scatter over the crumble topping.
Bake on the lowest shelf of your oven for 5 minutes, then turn on the broiler and bake for a further 5 minutes, or until the crumble topping is golden.
Serve immediately with thick cream, custard or vanilla ice cream, and a drizzle of the reserved poaching liquid.
For a campfire friendly version, toast your crumble topping slowly in a pan over medium-low heat, and then sprinkle directly over the fruit just before serving.