Trim excess skin and fat from chicken thighs, reserving the single layer of skin that covers the thigh meat.
Create a pocket between the skin and thigh meat using hands or a blunt utensil.
Mix together basil, Parmesan, garlic, sea salt, pepper, and a few drops of the olive oil.
Evenly divide the mixture between the chicken thighs, stuffing it into the pocket beneath the skin and evenly spreading over the thigh meat.
Heat remaining olive oil in a cast iron skillet over medium high heat.
Place chicken thighs skin side down in the hot skillet and cook for 5 minutes.
Flip the thighs and continue cooking on the stovetop for an additional 8-10 minutes.
Transfer the skillet to the 450 degrees Fahrenheit oven to finish the cook, baking for 15-20 minutes or until chicken reaches your preferred temperature.