01 - Set the air fryer to 375°F and allow it to preheat while you prepare the Brussels sprouts.
02 - In a large mixing bowl, toss the trimmed and halved Brussels sprouts with olive oil, garlic powder, smoked paprika, kosher salt, and black pepper until every piece is evenly coated.
03 - Place the seasoned Brussels sprouts in a single layer in the air fryer basket, making sure not to overcrowd them for even crisping.
04 - Cook for 12 to 15 minutes, shaking the basket halfway through, until the Brussels sprouts are golden-brown with crispy, caramelized edges.
05 - If desired, transfer the cooked sprouts to a serving bowl, sprinkle with grated Parmesan cheese, and toss gently to combine. Drizzle with fresh lemon juice just before serving.