Feijoas would have to be one of my all time favourite fruits, especially in crumble!
Growing up in New Zealand I had a big feijoa tree in the backyard that produced bucket loads of feijoas! and so Mum would make feijoa jams, cakes, and crumbles! The distinct sweet and sharp flavour of feijoas makes for a perfect alternative to green apples – making it a little different to your traditional apple and blackberry crumble.