Preheat the oven to 400°F.
Season the chicken thighs generously on both sides with salt, pepper, garlic powder, and Italian seasoning.
Heat the olive oil in a large oven-proof skillet over medium to medium-high heat. Add the chicken to the skillet, skin side down. Cook for 5 minutes, or until the skin is nice and crispy.
Flip the chicken thighs over to the other side and transfer the skillet to the oven. Bake for 15 to 20 minutes, until the chicken is cooked all the way through.
Transfer the skillet back to the stovetop. Remove the chicken from the pan, set aside, and cover to keep warm.
To the same skillet, add the butter, lemon juice, lemon slices, and capers, and using a rubber spatula, scrape up and mix in any bits stuck to the bottom of the pan.
Plate the chicken and pour the sauce over top. Garnish with fresh parsley.