Preheat the oven to 180C/350F. Toss the fruit in a bowl with the sugar and the Kirsch and allow it to macerate a bit while you make the crumble.
To make the crumble simply put all the ingredients for this into a food processor and pulse until you have a fine crumb.
Tip the filling contents into an appropriately sized pie or oven dish and top with the crumble topping which you can spread evenly over the top.
Bake for around 30 - 35 minutes until the topping is golden and the filling is just starting to bubble up the sides of the dish.
Notes
Storage Instructions for Nectarine and Apricot Crumble
Refrigeration: Store leftovers in an airtight container in the fridge for up to 3 days.
Freezing: You can freeze the assembled, unbaked crumble. Wrap tightly with plastic wrap and foil. Bake from frozen, adding an extra 10–15 minutes to the baking time.
Reheating: Warm leftovers in a preheated oven at 180°C/350°F for about 10 minutes or until heated through.