01 - Pat the chicken thighs and drumsticks dry with paper towels. Season both sides generously with salt and freshly ground black pepper.
02 - Heat olive oil and butter in a large sauté pan or Dutch oven over medium-high heat. Place the chicken pieces skin-side down and sear until the skin is deeply golden brown and crisp, about 5 minutes per side. Transfer the chicken to a plate and set aside.
03 - In the same pan with the rendered drippings, add the chopped onion and cook for 3 to 4 minutes until soft and translucent. Add the minced garlic and sliced mushrooms, continuing to cook until the mushrooms are tender and lightly caramelized.
04 - Stir in the tomato purée and cook for 1 minute to deepen its flavor. Pour in the dry white wine, using a wooden spoon to scrape up any browned bits from the bottom of the pan. Let the wine simmer for 2 minutes to reduce slightly.
05 - Add the diced tomatoes, chicken stock, fresh thyme leaves, and bay leaves. Nestle the seared chicken pieces back into the pan, skin-side up, and bring the liquid to a gentle simmer.
06 - Cover the pan with a tight-fitting lid and reduce the heat to low. Braise the chicken for 30 minutes, allowing the flavors to meld and the meat to become tender.
07 - Remove the lid and continue simmering uncovered for 10 to 15 minutes, letting the sauce reduce and thicken while the chicken finishes cooking through. The internal temperature of the chicken should reach 165°F.
08 - Discard the bay leaves. Transfer the chicken to a warm serving platter, spoon the sauce generously over the top, and garnish with freshly chopped parsley. Serve immediately.