Preheat your oven to 180°C / 350°F (160°C fan).
Season the chicken with 3/4 tsp of kosher salt and 1/2 tsp of black pepper.
Heat 3 tbsp of oil in a large, heavy, oven-proof pot over medium-high heat. Brown the chicken thighs, skin side down, for 2-3 minutes until deeply colored, then flip and cook for another minute. Transfer to a tray. Pull the skin over the drumsticks to cover the flesh as much as possible, then brown them on 3-4 sides, about 5 minutes in total. Set aside.
Remove any loose burnt bits from the pot, and add a bit more oil if needed. Cook the bacon for about 3 minutes until golden, then transfer to the tray with the chicken.
In the same pot, sauté the mushrooms for about 5 minutes until they turn golden. Remove and set aside in a separate bowl.
Sauté the onions in the pot for about 5 minutes until they develop nice golden patches.
Melt the butter in the pot. Once melted, add the minced garlic and cook for about 1 minute. Stir in the tomato paste and cook for 2 minutes. Sprinkle the flour over the mixture and cook for another 2 minutes.
Gradually stir in the beef stock while stirring continuously to help the flour dissolve smoothly. Add the reduced wine and mix until the flour mixture is fully incorporated and mostly lump-free (Note 8).
Return the chicken, bacon, mushrooms, thyme, bay leaf, salt, and pepper to the pot. Stir everything together.