This isn’t really a recipe. OK, it’s not a recipe at all. It’s a technique. Take any kind of crunchy cookie (no filling, so Fig Newtons are Right Out) or baked pate sucree or sablee or a chocolate cookie and whir it into dust/sand in the food processor.
If you want more texture in your sand–if you want to make pebbles instead of sand–bash up your cookie of choice with a rolling pin.
Use the resulting sand/pebbles as a base for a quenelle of ice cream so it doesn’t scoot all over the plate. Sprinkle it around as a garnish. Layer it with custard or ice cream to make a parfait. So simple, but striking, plus it adds another textural element to your plate.