Position a rack in the center of the oven and preheat to 425 degrees. In a large bowl, combine the olive oil, garlic, 1/2 tablespoon salt and 1/4 teaspoon pepper. Add the potatoes and toss to coat. Arrange the potatoes in a single layer on 2 large rimmed baking sheets. Pour a little water into each pan and bake for 30 minutes. Toss and bake for 15 minutes more.
Lower the heat to 350 degrees. Transfer the potatoes to paper towels to drain. Wipe the baking sheets dry, line with parchment paper and return the potatoes to the baking sheets in a single layer. Bake until golden-brown and crisp, 15 to 20 minutes. Toss with the parsley.