Step 1

Position rack in upper third of the oven; preheat to 500 degrees F.

Step 2

Toss potatoes, butter, oil, rosemary, salt and pepper in a large bowl. Arrange the potatoes in a single layer in a 9-by-13-inch metal baking pan. (Don't use a glass dish, which could shatter.) Roast, turning once, until browned, about 30 minutes.

Step 3

Carefully add broth, lemon juice and garlic to the pan. Continue roasting until most of the liquid is absorbed and the potatoes are very tender, 10 to 12 minutes more. Garnish with additional rosemary, if desired.