PLUM GRATIN Fast and simple and very good I've never cooked a plum before so I thought I would try a simple gratin just like the recipe for apple gratin. I peeled, pitted, and sliced the plums and added a bit more flour than in the apple gratin as the plums had more liquid. I added a bit of sugar and some butter, but skipped the cinnamon substituting a pinch of mace instead. Again 450 degrees for 15 minutes and voila! I served it with some whipped cream on top and it was very nice. I don't think I would go to the trouble again. It was an experiment. I think apples and peaches are much better and now they are always available. If all you had was plums, it would be a welcome treat.