01 - Preheat the air fryer to 375°F (190°C) according to the manufacturer's instructions.
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 evenly coated.
03 - Place the seasoned Brussels sprouts in a single layer in the air fryer basket, ensuring even spacing for proper air circulation.
04 - Air fry for 12 to 15 minutes, shaking the basket halfway through cooking, until the sprouts are golden brown and crispy at the edges.
05 - Transfer the cooked Brussels sprouts to a serving bowl and sprinkle with grated Parmesan cheese, tossing gently to coat if desired.
06 - Drizzle with fresh lemon juice just before serving. Serve immediately while hot and crispy.