I made a mistake and poured in the dry ingredients before I added the knife to the food processor so this is the only photo of them.
Add butter. Let the good processor do its magic or mix by hand.
Cut the plums.
Mix them with raw sugar...
Place the plums in a buttered cake tin.
Cover the plums with the crumble. Bake in the oven at 225 C for 15 min (check after 10 min.)
Dig in! Best served with vanilla icecream.