Drain the liquid off the baking sheet or transfer the clams to a clean baking sheet. Using a sharp knife, carefully cut the still-frozen clam meat from the shell, and then cut the meat in half. Use your hands to fully open and separate the shell halves.

Meanwhile, place the frozen clams on a rimmed baking sheet on the counter until they start to open, about 30 minutes.

Arrange an oven rack to the second-highest position and turn on the broiler.