Pat chicken thighs completely dry with paper towels.
Mix all spices in a large mixing bowl.
Rub spice mixture evenly on both chicken sides.
Let chicken rest for 10 minutes at room temperature.
Heat olive oil in cast-iron skillet over medium-high heat.
Place chicken skin-side down in hot skillet carefully.
Cook for 8 minutes without moving the pieces.
Flip chicken thighs using tongs very gently.
Add butter to the skillet around chicken pieces.
Cook for additional 15 minutes until internal temperature reaches 165°F.
Remove from heat and let rest 5 minutes.
Serve immediately while hot and crispy.