Preheat oven to 350 degrees.
Combine paprika, thyme, 1 1/2 teaspoons of salt, 1 teaspoon of pepper, lemon zest, onion and garlic powders in a small bowl. Mix until well combined. Set aside.
In a large ovenproof skillet over medium-high heat, heat the oil and one tablespoon of the butter. Add the chicken thighs, in batches if necessary, skin side down. Sear on all sides until golden brown, about 3-4 minutes per side. Transfer to a plate to cool. Remove all but one tablespoon of the fat from your skillet.
Over medium heat, add the onions to the skillet and cook until they begin to soften, about 8-10 minutes. Add the garlic and continue to cook for one minute. Add the celery and another teaspoon of salt and pepper. Cook for an additional 3 minutes.
Once the chicken thighs are cooled, pat them dry and rub the seasoning mix into all sides.
Add the rice and remaining one tablespoon of butter to the skillet and stir until all coated. Add the chicken to the skillet on top of the rice. Pour the chicken stock and 1/2 cup of water around and between the chicken, not over the top. Increase the heat to medium-high and bring to a simmer. Let the dish bubble for about 30 seconds. Cover with a lid or seal with foil and bake in the center of your oven for 35 minutes. Remove the lid. Spray the chicken with a little olive oil spray for extra crispy tops and continue to bake for 10 minutes, or until the liquid is absorbed and the internal temperature of the chicken is 165 degrees F. Remove from the oven and let stand for 5 minutes, Fluff the rice and garnish with parsley and serve.