01 - Preheat oven to 225°F or air fryer to 375°F and prepare baking sheets with parchment paper if using oven.
02 - Wash and dry zucchinis. Slice into 1/8 inch thin rounds using a mandoline or sharp knife for uniform thickness.
03 - Toss zucchini slices in olive oil until evenly coated.
04 - Combine sea salt, black pepper, garlic powder, smoked paprika, and Parmesan cheese if using.
05 - Sprinkle seasoning over zucchini slices and toss again to distribute evenly.
06 - Place zucchini slices in a single layer on baking sheets or in air fryer basket ensuring no overlap.
07 - Bake for 35 to 45 minutes at 225°F flipping halfway, or air fry for 10 to 15 minutes shaking basket once during cooking, until golden and crisp.
08 - Remove cooked slices and allow to cool for 5 minutes to achieve maximum crispness.
09 - Serve immediately or store in an airtight container for up to 2 days.