Spread the kale evenly on the baking sheet and roast until it has begun to steam and dry out around the edges of the leaves, about 5 minutes. Using tongs, toss the kale, keeping it evenly distributed, and rotate the baking sheet to ensure even cooking. Continue to roast until the kale is dark green and shatteringly crisp, 7 to 10 minutes more. Some of the edges may begin to brown. Serve hot or at room temperature soon after roasting.