Marinate the chicken - Transfer 1/2 cup chimichurri sauce to a large mixing bowl. Add 1 tablespoon oil, salt, and freshly cracked black pepper. Mix well to combine. Add the chicken thighs to the mixing bowl and, using your hands, mix well to completely coat the chicken in sauce.
Allow chicken to marinate for at least 30 minutes, time-allowing. Reserve remaining marinade for later use.
When ready to cook, preheat oven to 450 degrees F. Heat 2 tablespoons of olive oil in a large skillet over high heat. Heat pan until pan is hot, but oil isn't smoking. Add chicken and cook for 2 minutes before reducing heat to medium-high. Continue to cook an additional 4-6 minutes, occasionally rotating pan for even cooking. Flip chicken over and repeat on other side, cooking until golden.
Transfer skillet to the oven and continue to cook an additional 10-15 minutes (cooking time will vary) or until internal temperature registers 165 degrees F with a digital meat thermometer.
Remove skillet from the oven and transfer chicken to a clean plate to cool. Top each chicken thigh with 1-2 tablespoons of chimichurri sauce before serving. Enjoy!