1) use shortcrust pastry, roll it out to the size of your dish (I used a fluted tart dish), cover with greaseproof paper and baking beans, and bake blind for 10min at 190C. Remove the paper and beans and put back in the oven for another 5min.
2) while the pastry cools, prepare the cherry plums. Wash, cut in half and remove the stones. Put to one side.
3) put mascarpone in the tart. You want it to come up to 2/3 of your dish.
4) place the plums on the mascarpone, cut face down. Place as many as you can without overlapping them.
5) brush some warmed up cherry plum jam on the top (i'm sure other jams will do, such as apricot).
6) place in the oven at 180C for 20min
This is best left to cool and eaten the next day. As I said, this is the version that I made last week which wasn't really sweet. What I did this time was mix some icing sugar in with the mascarpone, about a couple of table spoons, and also added a drizzle of honey on the top. For some reason, this meant that I had to cook the tart for an extra 10min. Anyway, it was a success and everyone liked it!! I'm afraid I didn't have time to take a photo, but we did finish the evening with some of these little beauties ;-)