In a large bowl, season the chicken pieces generously with salt and pepper.
In a large, heavy-bottomed pot or Dutch oven, cook the bacon over medium heat until crisp. Remove the bacon and set aside, reserving the bacon fat in the pot.
Dredge the chicken pieces in flour, shaking off any excess. In the same pot with the bacon fat, brown the chicken in batches over medium-high heat. Remove the chicken and set aside.
Add the onions and mushrooms to the pot and cook until softened, about 5-7 minutes. Add the garlic and cook for another minute until fragrant.
Pour in the Cognac (if using) and carefully ignite it with a long match or lighter. Let the flames subside. (This step is optional but adds flavor.)
Pour in the red wine and chicken broth, scraping up any browned bits from the bottom of the pot. Add the thyme, bay leaf, and tomato paste. Bring to a simmer.
Return the chicken and bacon to the pot. Reduce the heat to low, cover, and simmer for 45 minutes to 1 hour, or until the chicken is cooked through and tender.
Remove the chicken from the pot and set aside. Increase the heat to medium-high and simmer the sauce until it has reduced slightly, about 10-15 minutes. Season with salt and pepper to taste.
Return the chicken to the pot and heat through. Garnish with fresh parsley before serving.
