Peel potatoes lightly with peeler. Trim ½-inch flat off each end using knife for stable stand. Potatoes now short fat cylinders.
Heat skillet over medium-high. Add butter using measuring spoon till foaming. Place potatoes flat-end down with tongs. Sear 5 minutes golden crusty. Flip tongs, sear other ends 5 minutes.
Tuck garlic and thyme sprigs between potatoes. Sprinkle salt, pepper from measuring spoons.
Pour chicken stock around edges using measuring cup till halfway up potatoes. Bring to simmer. Cover lid tight. Reduce heat low, braise 30-35 minutes. Stock reduces syrupy, potatoes knife-tender.
Uncover. Baste potatoes with spoon in pan juices 5 minutes till glossy shine. Pull off heat. Rest 2 minutes.
