Step 1: Preheat your oven to 300°F (150°C). Line two large baking sheets with parchment paper.
Step 2: Wash the kale thoroughly under cold running water. Remove the thick, fibrous stems by tearing or cutting the leaves away from the center rib. Discard the stems.
Step 3: Thoroughly dry the kale leaves using a salad spinner and then pat them completely dry with a clean kitchen towel or paper towels. This step is crucial for crispy kale chips.
Step 4: Tear the dry kale leaves into bite-sized pieces, roughly 1-2 inches. Place them in a large mixing bowl.
Step 5: Drizzle the kale with 1-2 tablespoons of olive oil. Use your hands to gently massage the oil into the leaves, ensuring every piece is lightly coated but not drenched.
Step 6: Sprinkle the kale with garlic powder, sea salt, black pepper, nutritional yeast (if using), and grated Parmesan cheese (if using). Toss everything together really well until all the kale pieces are evenly coated with the seasonings.
Step 7: Arrange the seasoned kale in a single layer on the prepared baking sheets. Do not overcrowd the pan; use two sheets or bake in batches if necessary to ensure proper crisping.
Step 8: Bake for 15-20 minutes, or until the kale is very crispy and slightly browned but not burnt. Keep a close eye on them, as baking times can vary. Check around the 10-minute mark.
Step 9: Remove the kale chips from the oven and let them cool completely on the baking sheets. They will crisp up even further as they cool.
Step 10: Serve immediately for the best crispness. Store any leftovers in an airtight container at room temperature for up to 2-3 days, though they are best enjoyed fresh.