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. Once the fat is shimmering, place the chicken skin-side down and sear until deeply golden brown, about 5 minutes per side. Transfer the chicken to a plate and set aside.
03 - In the same pan with the rendered drippings, sauté the chopped onion for 3 to 4 minutes until soft and translucent. Add the minced garlic and sliced mushrooms, cooking until the mushrooms have released their moisture and are lightly browned.
04 - Stir in the tomato purée and cook for 1 minute to deepen its flavor. Pour in the dry white wine, scraping up any browned bits from the bottom of the pan. Let the wine simmer for 2 minutes to cook off the alcohol.
05 - Add the diced tomatoes, chicken stock, thyme, and bay leaves. Nestle the seared chicken pieces back into the pan, skin-side up. Bring the liquid to a gentle simmer.
06 - Cover the pan with a tight-fitting lid and reduce the heat to low. Cook for 30 minutes, allowing the chicken to braise and absorb the flavors of the sauce.
07 - Remove the lid and continue simmering uncovered for 10 to 15 minutes, until the sauce has thickened to a rich consistency and the chicken is cooked through to an internal temperature of 165°F.
08 - Discard the bay leaves. Transfer the chicken to warmed plates, spoon the sauce generously over each piece, and garnish with freshly chopped parsley before serving.