Prepare the Potatoes
Peel the potatoes and cut them into even-sized rounds, about 2 inches thick. Rinse them under cold water and pat dry with a paper towel.
Sear the Potatoes
In a large, oven-safe skillet, heat the butter and olive oil over medium-high heat until the butter is melted and sizzling. Season the potatoes with salt and pepper on both sides, then place them in the skillet. Sear the potatoes for about 5-6 minutes per side, or until they develop a golden-brown crust.
Add Garlic, Herbs, and Stock
Carefully add the garlic cloves and thyme (or rosemary) to the skillet. Pour in the stock, making sure it reaches about halfway up the sides of the potatoes.
Bake the Potatoes
Preheat your oven to 400°F (200°C). Transfer the skillet to the oven and bake for 30-35 minutes, or until the potatoes are tender and the stock has reduced, creating a rich sauce. Baste the potatoes with the pan juices halfway through cooking for extra flavor.
Serve
Remove the skillet from the oven. Discard the garlic and herb sprigs, then carefully transfer the potatoes to a serving dish. Spoon some of the reduced pan sauce over the top.