- Peel the orange, grate the peel and squeeze the juice of pulp; grate the ginger; set them aside. Preheat oven at 200*F.
- Put plums in an oven proof dish. Top with cinnamon, honey, orange peel, ginger and orange juice.
- Cook in the oven for 15 minutes. At the same time, combine muesli, spread and flour in a bowl and mix well to form the crumb topping.
- Remove from the oven and scatter the crumble mixture over and continue to cook for more 20 minutes.
- Serve with low-fat custard.