How to Make It
Pat the chicken thighs with paper towels to remove excess moisture, then trim and discard any big pads of fat. If the thighs are large or super-uneven in thickness, butterfly them. Lay the thigh, smooth-side down, on your cutting board. Wielding your knife horizontally, slash the big mound of flesh to create a flap of meat, stopping just shy of cutting all the way through. Fold back the meat flap that you just created. The thigh should now be about 50 percent longer and relatively even in thickness. If the result seems awkwardly large, cut it crosswise into two smaller, squareish pieces. Set aside.
In a large bowl, stir together the garlic, five-spice powder, honey, hoisin, soy sauce, ketchup, and sesame oil. Remove 3 tablespoons and set aside for glazing the chicken. Add the chicken to the bowl, coating the pieces well. Cover with plastic wrap and marinate at room temperature for 30 minutes, or refrigerate up to 24 hours (return to room temperature before cooking).
Lightly oil a cast-iron stove-top grill pan and set over medium-high heat. Add the chicken and cook for 6 to 10 minutes, turning several times. To test for doneness, pierce the flesh with the tip of a knife; the chicken is cooked when clear juices flow out. During the last 2 minutes, when the chicken feels relatively firm, baste with the reserved marinade to freshen flavor and add sheen. Transfer to a platter and let rest for 5 to 10 minutes before serving.