Heat the oven to 500°F.

Stir 2 tablespoons melted unsalted butter, 2 tablespoons olive oil, 3/4 teaspoon kosher salt, and 1/2 teaspoon black pepper together in a large bowl until combined. Add 2 pounds sweet potato rounds and toss well to coat.

Transfer the potatoes cut-side up to a 9x13-inch metal baking pan or rimmed baking sheet and arrange in a single layer. Drizzle any remaining butter mixture over the potatoes.

Roast until the sweet potatoes easily release from the pan with tongs and the bottoms are light golden-brown, 12 to 15 minutes. Flip the sweet potatoes and roast until the bottoms and tops are deep golden-brown, 12 to 15 minutes more.

Meanwhile, whisk 1 cup low-sodium vegetable broth, 1 tablespoon honey, and 2 to 3 teaspoons Calabrian chili paste together in a liquid measuring cup.

Remove the pan from the oven. Carefully pour the broth mixture into the pan and add 4 peeled and smashed garlic cloves. Return to the oven and roast until the sweet potatoes are very tender and most of the broth is absorbed, 12 to 15 minutes.