Place the kale in a large mixing bowl, and drizzle with duck fat. Toss well to coat evenly in fat. Arrange in a single layer on a rimmed baking sheet, being sure not to crowd or overlap. Season with salt and pepper, then sprinkle with Parmesan.
Bake for 9-12 minutes, turning the pan partway through cooking time, until the kale is crisp and lightly browned on the edges. Serve piping hot.