Ren, you've probably already made it but just wanted to add that I do a similar one to Sangie. Except I use either Pink Lady or Royal Gala apples (much sweeter) and I pre-cook them in a saucepan with a couple of tablespoons of water and a couple of spoonfuls of caster sugar and cinnamon. Then I chuck them in a dish and put the crumble mixture on top and bake that in the oven until golden brown.