Air fry the potatoes whole. Preheat the air fryer to 400°F (200°C). Add the potatoes to the basket in a single layer and cook for 20 minutes, until a fork slides in easily.
Smash them. Remove the tray and use a potato masher, a large fork, or the bottom of a glass to press each potato flat. Top with a small pat of butter and season with salt and pepper.
Air fry again. Return the tray to the air fryer and cook for another 15 minutes, until the edges turn golden and crispy.
Serve. Serve hot, straight from the basket.
Notes
Don't overcook your potatoes. They can get overcooked, and be too soft. Then, they'll fall apart when you cook them.
Put parchment in your air fryer basket to help the smashed potatoes not to stick. This also makes clean up a breeze.
For extra crispy potatoes, place them under the broiler for a few minutes at the end of the cooking time.