Remove any loose or damaged outer leaves from the cabbage. Slice the head through the core into 1-inch thick rounds, keeping the core intact so each steak holds together. You should get 3 to 4 solid steaks from one large head.
In a small bowl, whisk together the olive oil, garlic powder, smoked paprika, onion powder, salt, and black pepper.
Brush both sides of each cabbage steak generously with the seasoned oil mixture, making sure to get some between the layers where possible.
Preheat the air fryer to 380F. Place the cabbage steaks in a single layer in the basket, working in batches if needed. Air fry for 8 minutes.
Carefully flip each steak and air fry for another 7 to 8 minutes until the edges are nicely charred and crispy while the centers are fork-tender.
Transfer to a serving plate, drizzle with melted butter and fresh lemon juice, and finish with a generous sprinkle of fresh parsley. Serve immediately while hot.