Weigh the apple and the rhubarb so you can work out how much sugar to use. The rule of thumb I use is the amount of sugar to stew with the fruit is a quarter of the weight of the fruit. So if your fruit weighs 800g you would use 200g of sugar.
After you have worked this out put the apple and rhubarb pieces into a pot and then tip in the correct amount of sugar.
Put the pot on the stove top at a moderate heat and give it all a good mix so as to coat the apple and rhubarb with the sugar.
Leave it on the heat and stir occasionally until the fruit is tender and has broken down. You still want to have chunks of fruit so don’t cook it too long or else you will end up with a thick sludge – about 15 minutes should do it.
While the fruit is stewing get a large bowl and tip in the coconut, flour, rolled oats, almonds and macadamia nuts and give them all a good stir.
Heat the butter and maple syrup together in a separate bowl until melted stirring to combine then tip this into the combined dry ingredients. Mix thoroughly – this is your crumble topping.
Get a rectangular or oval shaped oven proof dish and use the extra butter to grease.
Tip in the stewed fruit and all the juices then cover with the crumble mixture.
Bake in a hot oven – 180 ° for about 25 – 30 minutes or until the crumble is a lovely golden brown.