Preheat oven to 425 °F (220 °C).

Dry the potato cylinders thoroughly with paper towels; season all sides generously with salt and pepper.

In a large oven‑safe skillet, melt butter with olive oil over medium‑high heat. When bubbling, add potatoes cut‑side down and cook without moving until deep golden brown, about 4–5 minutes.

Flip the potatoes and add garlic cloves and thyme sprigs around them. Sear the second side for 3–4 minutes until browned.

Carefully pour broth into the skillet (it should sizzle). Transfer skillet to the oven.

Roast for 15–20 minutes, basting the tops occasionally with pan juices, until potatoes are tender inside (test with a skewer).

Remove from oven, discard garlic skins and thyme sprigs, spoon pan juices over the potatoes, and serve hot.