3 pounds potatoes, halved or quartered depending on size
½ cup olive oil
Kosher salt and freshly ground black pepper
4 oz. finely grated Parmesan
¾ cup chopped fresh flat-leaf parsley
1 teaspoon finely grated lemon zest
1 tablespoon fresh lemon juice
1 teaspoon crushed red pepper flakes
Place a rack in upper third of oven; preheat to 400°. Toss potatoes and oil in a large bowl; season with salt and pepper. Place potatoes, cut side up, on a wire rack set inside a rimmed baking sheet; reserve bowl. Roast until golden brown and cooked through, 30–35 minutes. Transfer to bowl; toss with Parmesan. Return potatoes to rack and roast until Parmesan is brown and crisp, 10–12 minutes.
Toss potatoes in same bowl with parsley, lemon juice, and red pepper flakes. Top with lemon zest just before serving.