Peel the Yukon Gold potatoes and cut them into evenly sized chunks.
Place the potatoes in a pot of salted boiling water. Cook for 15–20 minutes, or until fork-tender.
Drain the potatoes well and return them to the warm pot. Add the butter and mash until mostly smooth.
Add the garlic powder, onion powder, and all-purpose seasoning. Gradually add the half-and-half and mash until creamy and smooth. Adjust the seasoning to taste.
Pat the chicken thighs very dry with paper towels. This helps the skin get extra crispy.
Lightly coat the chicken with olive oil. Season both sides with Cajun seasoning, paprika, cayenne pepper, and garlic powder.
Sprinkle the cornstarch over the chicken and rub it in evenly, making sure the chicken is lightly coated.
Place the chicken skin-side down in the air fryer. Air fry at 375°F for 18–20 minutes, flipping halfway through.
Continue cooking as needed until the chicken reaches an internal temperature of 165°F and the skin is crispy.
Spoon the creamy mashed potatoes onto a plate and place a crispy Cajun chicken thigh on top.
Serve immediately and enjoy!