could i use prune plums

I've made this, and I'd think you could sub just about any stone fruit you desire. You could also mix peaches and nectarines. It's a stunning presentation.

Many thanks!! I have made the peach tart several times to great acclaim..peach season is finished here..so am delighted to hear that plums will work!! Anxiously awaiting cookbook. Barb

Yes, you can!