Preheat an oven to 400 degrees.
Pat the chicken thighs dry with paper towels, then sprinkle with the salt and pepper.
Heat a dutch oven over medium high heat. Once warm add in the olive oil and allow it to come to a shimmer. Add in half the chicken thighs and brown on the first side, about 3 minutes, flip and brown on the second side for an additional 3 minutes and then remove to a plate. Continue with the second batch of chicken thighs.
While the chicken is cooking mix the chopped parsley, chopped olives, capers, lemon zest, lemon juice, and garlic.
Once all of the chicken thighs are removed to a plate, add the chopped onion to the pot, followed by the parsley olive mixture.
Saute for one minute.
Add in the chicken stock, and scrape any brown bits off the bottom of the pot with the back of a wooden spoon to allow the fond (brown bits on the bottom of the pan) to flavor the stock. It's good stuff down there.
Add in the rice and the chicken along with any juices that accumulated on the plate. Put the lid on the pot and place it in the oven. Cook for 20 minutes.
After twenty minutes remove the pot from the oven and fluff all the rice with a fork. Serve it warm and garnish with the additional tbsp of parsley.