01 - Set the oven to 300°F and line a baking sheet with parchment paper.
02 - Wash the kale leaves thoroughly and dry completely. Tear into bite-sized pieces, discarding tough stems.
03 - Toss the kale with olive oil, sea salt, black pepper, and garlic powder in a large bowl until evenly coated.
04 - Spread the kale in a single layer on the prepared baking sheet.
05 - Bake for 12 to 15 minutes, turning once halfway through, until the kale is crispy but not browned.
06 - Remove from oven, sprinkle with lemon zest, and add Parmesan cheese and chili flakes if desired. Serve immediately.