1. Preheat oven to 425 degrees Fahrenheit.
2. With a large, sharp chef’s knife, cut each sweet potato in half lengthwise, then cut each half in half, and each of the quartered wedges in half again, to make 16 thin wedges in total. Spread out in one layer on a large baking sheet lined with Gefen Parchment Paper. (Use two baking sheets if the sweet potatoes are overlapping–they’ll steam instead of crisp if they’re too crowded.) Drizzle with olive oil and season with kosher salt and pepper (and rosemary and chili powder if using).
3. Bake for 20 minutes until beginning to soften and caramelize. Remove from oven and flip with a spatula. Continue to bake for another 15 to 20 minutes until golden and crispy.