Wash kale to remove debris, and dry kale using a salad spinner or pat dry with a paper towel to remove excess water.
Remove the stalks and tough veins that run in the middle off the leaves using a sharp knife. Cut the leaves into bite-size pieces and set aside in a large bowl.
In a high-speed blender, add cashews, water, bell peppers, nutritional yeast flakes, lemon juice, onion powder, garlic powder, salt, and cayenne pepper. Process until smooth.
Pour cashew sauce over kale leaves and massage to coat.
Place kale leaves in a single layer in the basket of the air fryer. Bake at 370 degrees F for 7 minutes, shaking the basket halfway.
Transfer the baked kale leaves on a baking sheet, kale will continue to crisp up. Repeat with the remaining kale leaves.