Prep the potatoes: Scrub the sweet potatoes well and pat dry. Keep the skins on for texture and structure.
Make the Hasselback cuts: Place a potato between two wooden spoons or chopsticks to act as guides.
Slice crosswise every 1/8 to 1/4 inch, stopping just before cutting through the bottom so the potato stays intact. Repeat with all potatoes.
Air fryer preheat: Preheat the air fryer to 375°F (190°C) for 3–5 minutes. This helps the edges crisp right away.
Mix the seasoning: In a small bowl, combine melted butter, olive oil, garlic, salt, pepper, smoked paprika, cinnamon (if using), and thyme.
If you want a touch of sweetness, whisk in the honey or maple.
Coat the potatoes: Gently fan open the slices with your fingers. Brush the seasoning mixture all over the potatoes, getting between as many slices as you can. Reserve a tablespoon for basting later.
Air fry round one: Arrange the potatoes in the basket, cut side up, with a little space between each.
Cook for 18–22 minutes.
Baste and finish: Open the basket and brush with the reserved mixture. If the slices aren’t opening much, gently nudge them apart with tongs. Continue air frying for another 10–15 minutes, until the edges are crisp and the centers are tender when pierced.
Total time is usually 28–37 minutes, depending on size.
Garnish and serve: Sprinkle with fresh herbs. Add a squeeze of lemon for brightness if you like. Serve hot.