Crumble topping:
Preheat oven to 350 F or 200 C
If you are making Apple Crumble on its own, I often add cinnamon and a bit of porridge oats into the crumble mixture and a dash of cinnamon into the fruit too.
You know the size of your own casserole dish and you'll know when you've layered enough fruit into the bottom of it.
Sprinkle the crumble topping on the top of the fruit and pop it in the oven.
Bake it until the top is toasty brown and the fruit juices are bubbling up in a couple of places.
Remove it from the oven and LET IT COOL for a little while before serving. If you serve this straight from the oven, you'll burn yourself and possibly anybody else who eats it at this temperature.