Position rack in upper third of oven; preheat to 500°F.
Combine sliced potatoes, 2 tablespoons oil, ¾ teaspoon salt and ½ teaspoon pepper in a large bowl; toss until evenly coated. Arrange in a single layer in a 9-by-13-inch metal baking pan. (Don’t use a glass dish, which could shatter.) Scatter 2 tablespoons cubed butter over the potatoes. Roast, flipping once using a spatula, until browned, about 30 minutes.
Combine ½ cup broth, 2½ tablespoons lemon juice and the minced garlic in a liquid measuring cup. Carefully add the broth mixture to the pan. Continue roasting, undisturbed, until the potatoes are very tender and most of the liquid is absorbed, 8 to 10 minutes. Remove from oven. Immediately add the remaining 1 tablespoon cubed butter, carefully swirling the pan until the butter is fully melted and emulsified.
Sprinkle with 1 tablespoon parsley and 1 teaspoon lemon zest before serving. Recipe developed by Jasmine Smith
