I stumbled on this recipe a couple years ago out of necessity. My mother-in-law had bought some little purple grapes (which I now know are seedless Concord grapes) at our local farm market. But they were very ripe, and I had too many left to eat before they spoiled.
Enter Italian fresh purple grape cake.
This is awesome at any time of year, but the seedless Concord grapes are only available in the fall (at least in my area). However, if you wash and dry the grapes off the vines, they freeze very well in containers or ziplock bags. Just measure and defrost when you need them.
With some fresh homemade whipped cream on top, and perhaps a sprig of fresh mint, this can be a very festive and different dessert for your holiday table.