Prepare the fruit:Core and chop the apples into bite-sized pieces, leaving the skins on. Place them in a pot with the frozen blueberries, water, and the other stewed fruit ingredients (ground cinnamon and ground ginger).
Cook the fruit:Bring the fruit mixture to the boil, then reduce to a simmer. Stir occasionally and cook for about 20 minutes, or until the fruit has broken down.
Prepare the crumble topping:If using coconut oil, melt it first by gently heating it in a pan. Mix all the crumble ingredients together in a bowl, including the oil (sunflower or coconut).
Assemble the crumble:Once the fruit has stewed, transfer it to a baking dish (we used a 30cm ceramic dish) and spread it out evenly. Spread the crumble topping evenly over the fruit.
Bake:Place the dish in the preheated oven and bake for about 25 minutes at 170°C, or until the top of the crumble turns golden.Serve and enjoy!