Preheat the oven to 450°F (230°C). High heat is key to browning and that “melting” center. Place a sturdy, rimmed baking sheet on the middle rack as the oven heats to get it hot.

Prep the potatoes. Peel the sweet potatoes. Slice into thick rounds, about 1 to 1.25 inches wide. Try to keep them even so they cook at the same rate.

Season well. In a large bowl, toss the rounds with melted butter, olive oil, 1.5 teaspoons kosher salt, and 1/2 teaspoon black pepper. Add the crushed garlic and a few thyme sprigs to the bowl so their oils start to mingle.

Arrange on the hot pan. Carefully pull the hot sheet from the oven. Remove the thyme and garlic from the bowl (you’ll use them later). Lay the slices flat in a single layer with space between each piece. This helps crisp the edges.

Roast, flip, roast again. Roast for 15 minutes. Flip each round with a thin spatula. Roast another 12 to 15 minutes until the bottoms are caramelized and the sides look blistered.

Add the steam-and-glaze step. Scatter the reserved garlic and thyme on the pan. Pour in the broth around the potatoes, not over them. If you want a touch of sweetness, whisk 1 to 2 teaspoons maple syrup into the broth before adding. Return to the oven for 10 to 12 minutes, until most of the liquid is absorbed and the centers are very tender.

Finish and serve. Transfer to a serving platter. Spoon any pan juices over the top. Add a pinch of flaky salt, a dusting of lemon zest, or a light sprinkle of red pepper flakes if you like heat. Serve hot.