In a large bowl, whisk together the flour, baking powder, garlic powder, onion powder, salt, and cayenne pepper. Add the cold butter cubes and use a pastry cutter or your fingertips to work the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces remaining.
Stir in the shredded cheddar cheese until evenly distributed. Pour in the cold buttermilk and stir gently with a fork until a shaggy, slightly sticky dough forms. Do not overmix.
Drop the dough by heaping spoonfuls (about 1/4 cup each) onto a parchment-lined plate to form 8 rough, rustic mounds. These should look like drop biscuits, not smooth rounds.
Preheat the air fryer to 330°F for 2 minutes.
Line the air fryer basket with a piece of parchment paper with small holes poked through it for airflow. Place the biscuits in the basket with about 1 inch of space between each one. You may need to cook in two batches of 4.
Air fry for 10 to 12 minutes until the biscuits are risen, golden on top, and cooked through in the center.
While the biscuits cook, prepare the garlic butter topping by combining the melted butter, garlic powder, and fresh parsley. As soon as the biscuits come out of the air fryer, brush the tops generously with the garlic butter.
Serve warm. These are best eaten right away when the cheese is still gooey and the tops are glistening with garlic butter.