Start by patting the boneless skinless chicken thighs dry with paper towels. Trim any excess fat and set aside.

In a small mixing bowl, whisk together the soy sauce, dark soy sauce (if using), minced garlic, brown sugar, and allspice until well combined. Set the marinade aside.

Place a large skillet over medium-high heat, add the olive oil and sesame oil, and heat for 1-2 minutes until shimmering.

Add the chicken thighs to the hot skillet in a single layer and brush half of the marinade over the top. Cook undisturbed for about 5 minutes until browned.

Carefully flip the chicken thighs and brush the remaining marinade over the cooked side. Continue cooking for an additional 9-13 minutes until cooked through.

Monitor the glaze's caramelization and adjust the heat to prevent burning, aiming for a beautifully glazed and slightly crispy chicken.

Remove the skillet from heat and let the chicken rest for a couple of minutes before serving. Enjoy warm over rice or with vegetables.