Trim the woody stem ends off each Brussels sprout and pull away any yellowed or bruised outer leaves. Slice each sprout in half lengthwise through the stem so both halves hold together.

Pat the halved sprouts thoroughly dry with clean paper towels. Removing excess surface moisture is the essential secret to achieving crispy, blistered leaves rather than steamed sprouts.

In a large mixing bowl, toss the halved Brussels sprouts with olive oil, garlic powder, smoked paprika, sea salt, black pepper, and crushed red pepper flakes until evenly coated in the seasoning.

Preheat your air fryer to 390°F (198°C) for 3 minutes. Lightly coat the air fryer basket with olive oil spray (do not use aerosol non-stick spray on nonstick baskets).

Transfer the seasoned Brussels sprouts into the air fryer basket in a single layer, arranging as many cut-side down as possible. If cooking a double batch, cook in batches to avoid overcrowding.

Air fry at 390°F (198°C) for 10 minutes. At the 6-minute mark, pull out the basket and shake vigorously to redistribute the sprouts so all sides crisp evenly.

At 10 minutes, open the basket. Add the minced garlic and sprinkle ⅓ cup of the finely grated Parmesan cheese evenly over the sprouts. Shake gently to coat.

Air fry for an additional 2 to 3 minutes until the Parmesan is melted, golden brown, and bubbling, and the sprout edges are shatteringly crisp and caramelized.

Transfer the hot Brussels sprouts to a serving bowl. Immediately squeeze fresh lemon juice over the top, sprinkle with the remaining Parmesan cheese, and drizzle with aged balsamic glaze if desired. Serve piping hot!