How to Make It
Preheat the oven to 400°. Spread a 1/2-inch-thick layer of rock salt on a large baking sheet and across the bottoms of 6 large plates.
Arrange the reserved oyster shells on the baking sheet. Put 1 oyster in each shell and top with 2 to 3 tablespoons of the sauce, spreading the sauce evenly out to the edge of the shell to completely cover the oyster. (Alternatively, transfer the sauce to a pastry bag fitted with a plain tip and pipe the sauce over the oysters.)
Bake until the sauce is lightly browned and the oysters begin to curl around the edges, about 20 minutes.
Using tongs or a spatula, carefully transfer the hot shells to the salt-covered plates and serve immediately.