Preheat oven to 400°F.
Prep the Chicken: Pat the chicken completely dry with paper towels. Then rub the chicken with olive oil and generously season with salt and pepper.
Cook the Chicken: Set cast iron pan over medium-high heat. Then heat 1 tbsp of olive oil in the pan. Then sear the chicken skin side first for about 4-5 minutes. Then flip the chicken and sear for another 4-5 minutes. Then transfer the chicken to a plate. If the chicken looks slightly undercooked, it's ok because it will finish cooking in the oven.
Make the Creamy Lemon Sauce: In the same cast iron pan (over medium heat), add the butter and olive oil. Then add the leeks and onion and sauté for about 5 minutes until they become translucent and tender. Then add the garlic and cook for an additional 1-2 minutes. Add the wine and chicken stock and let it simmer for about 4 minutes. Whisk in the Boursin, lemon juice, lemon zest, salt and black pepper. Then tuck in the thyme and lemon between each piece of chicken.
Bake: Transfer the chicken thighs to the sauce. Then tuck the lemon slices around each thigh and add the thyme sprigs on top. Transfer the pan to the oven and roast uncovered for about 10-15 minutes.
Serve: Serve immediately while hot with a side of crusty bread, polenta or pasta. Enjoy!
