This is a very simple crumble to make and I often get my children to make it for me while I'm cooking the main meal. Blueberry and blackberry is a delicious combination and I use frozen berries that I always have to hand in the freezer so this recipe can be whipped up at any time. Feel free to substitute with your favourite fillings - rhubarb and ginger; apple and blackberry or pear and ginger are other favourites.
