DH bought home some rhubarb and cooking apples in the week, I am going to make up some crumbles and a pie to freeze, but I want to use up some yoghurt that I have in the fridge. I have a great blueberry muffin recipe that I often mess about with to use different fruits, add nuts etc. can I use that and just replace the blueberries with rhubarb and apple? and will I have to cook the fruit first as I would for crumble?