In a small bowl, combine the panko, butter, a pinch of salt and the Parmesan. In another small bowl, combine the thyme, garlic, lemon zest, a large pinch of pepper and the cream.
Divide the bay scallops between two individual gratin dishes. Pour half the cream mixture over each dish, then sprinkle each evenly with the panko mix. At this point, the scallops can be wrapped and refrigerated for up to 24 hours or baked immediately.
Preheat oven to 400 degrees. Place the gratin dishes on a baking sheet and bake for 8 to 10 minutes, or until cream is bubbling all over and the crumbs are browned.