Season the chicken pieces generously with salt and black pepper. Set aside.

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

Sear the chicken pieces in the bacon fat until golden brown on all sides, about 5-6 minutes per side. Remove chicken and set aside.

Add the mushrooms and pearl onions to the pot. Cook until the mushrooms are browned and onions are softened, about 5 minutes. Add garlic and cook for 1 more minute.

Stir in the tomato paste and flour, cooking for 1-2 minutes to remove the raw flour taste.

Pour in the red wine and chicken stock, scraping up any browned bits from the bottom of the pot. Add the 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 very tender.

Remove the chicken pieces and set aside. Increase heat to medium and simmer the sauce for 10-15 minutes to reduce slightly. Stir in butter for richness.

Return the chicken to the pot to warm through. Garnish with fresh parsley before serving.