Crumble is one of those puddings which can have any seasonal filling added to it ... tonight we had rhubarb and apple. For the filling, I just simmer the fruit with water and a little sugar to taste. If it's rhubarb I add a little ground ginger too :~)
Crumble topping recipe
8oz plain white flour
8oz plain wholemeal flour
Rub the flour and butter together until it resembles breadcrumbs and then stir in the sugar.
Variations: You can swap (weight for weight) the flour for oats or chopped nuts although it's best not to go below 8oz flour as it acts to bind the crumble together.