Prepare the chicken: Pat the chicken pieces dry with paper towels. Season generously with salt and black pepper.

Cook the bacon: In a large Dutch oven or heavy pot, cook the diced bacon over medium heat until crispy. Remove with a slotted spoon and set aside, leaving the fat in the pot.

Brown the chicken: Sear the chicken pieces in the bacon fat until golden brown on all sides. Work in batches if needed. Remove and set aside.

Sauté vegetables: In the same pot, add the pearl onions and mushrooms. Cook until the onions are lightly browned and the mushrooms release their moisture. Add garlic and cook for 1 minute.

Deglaze and simmer: Stir in the tomato paste and flour, then pour in the red wine and chicken stock. Add thyme and bay leaves. Return the chicken and bacon to the pot. Bring to a simmer, then cover and cook on low heat for 1.5 to 2 hours, until the chicken is tender.

Finish and serve: Remove the bay leaves and thyme sprigs. Stir in butter for a glossy finish. Adjust seasoning if needed. Garnish with fresh parsley before serving.