Apple Crumble Slice Ingredients Crumble Topping: 185 g (1 1/4 cups) plain (all purpose) flour 1 teaspoon baking powder 125 g (1 stick) butter 3/4 cup (165 g) caster (superfine ) sugar Apple Filling: 5 apples (I used a combination of granny smith and royal gala) 1 tablespoon butter 1/2 teaspoon ground cinnamon 1