We grew the plums, we picked, washed and de-stoned them.
I laid the plum halves on the dish, skin side down and sprinkled them with sugar. Then I made a topping out of:
85g plain flour
– mixed into crumbs
4 tablespoons brown (muscovado) sugar
1 small handful medium ground semolina
– stirred into the mix
And I baked the whole lot at 190 degrees Celsius for 15 mins: lovely crunchy crumble!