Step 1

In a small bowl, mash together the butter, mustard, thyme, zest, salt, and pepper until well combined. Refrigerate until ready to use.

Step 2

Position an oven rack 5 to 6 inches from the broiler element and heat the broiler to high. Line the bottom of a broiler pan with foil and replace the perforated top part of the pan. Arrange the chops on the pan. Season both sides of the lamb generously with salt and pepper. Broil until the first side is wellbrowned, about 8 minutes. Turn the chops over with tongs and continue to broil until they’re well browned and the center is cooked to your liking, 3 to 5 minutes longer for medium rare (cut into a chop near the bone to check).

Step 3

Transfer the lamb to serving plates and top each chop with a dab of the flavored butter. Serve hot.