Pierce potatoes with a fork on all sides. Boil water and add potatoes. Boil 15-20 minutes, until the potatoes are fork tender.
Meanwhile, in a medium bowl, whisk together the olive oil, rosemary, garlic powder, salt, and pepper. Set aside.
Preheat the air fryer at 400°F for 2-3 minutes.
When potatoes are fork tender, drain and place onto a cutting board. One at a time, gently smash down each potato with the bottom of a glass or mug. The thinner the potatoes, the crispier they will get. I like to smash them until they are between ¼ to ½-inch thick.
Either spray the bottom of the air fryer basket(s) with cooking spray or line with parchment paper.
Using a basting or pastry brush, brush the olive oil mixture onto the top of each smashed potato.
Place potatoes in a single layer in air fryer baskets, leaving about an inch apart. You may need to work in batches.
Air fry at 400*F for 18-20 minutes, until the tops of the potatoes and edges are golden brown.
Allow them to rest for about 1 minute in the air fryer before carefully transferring to a plate with a thin spatula.
Notes
Makes about 4-5 side dish servings.Storage: allow to cool then store in an airtight container in the refrigerator for up to 3 days. Reheat in the air fryer.