Method
1. Set the oven
2. Measure out all the dry ingredients for topping into a
    large bowl
3. Rub in margarine into the dry ingredients until the
    mixture resembles breadcrumbs
4. Peel, quarter and core the apple
5. Slice half the apple and coat with lemon juice then
    place into the casserole dish
6. Sprinkle on the raisins and cover with the other
    half of the apple
7. Sprinkle the crumble mixture on top
8. Bake in the oven for 30-35 minutes until the
    topping is crisp and apples are soft