1.Preheat the oven to 350°F. Heat the olive oil over medium heat in a Dutch oven. Add the bacon and cook until crispy, about 8 to 10 minutes. Transfer bacon to a plate with a slotted spoon.
2.Pat chicken pieces dry with paper towel and season with salt, pepper, and garlic powder. Add the chicken thighs skin side down to the leftover bacon grease. Sear for about 5 minutes each side, until skin is rendered, crispy and browned. Transfer chicken to the plate with the bacon. Repeat with chicken drumsticks. Set aside.
3.Add the onions, carrots, salt, and pepper to the pan and cook over medium heat for 5 minutes, while stirring occasionally, until the onions are transparent and lightly browned. Add the garlic and cook until fragrant, about 1 minute.
4.Pour in the cognac, red wine and chicken broth; stir to combine. Add the thyme, bacon, chicken, and any juices leftover from the plate into the pot. Bring to a simmer, then cover with a lid and transfer to the oven for 20-30 minutes, or until the chicken is cooked through and no longer pink in the middle.
5.While chicken is in the oven, melt 2 tablespoons of butter in a pan over medium heat. Cook the mushrooms for 8 to 10 minutes, until soft and browned. Set aside. Mash 1 tablespoon butter with flour. Set aside.
6.Remove casserole from oven and place on stove. Turn on stove to medium heat. Add butter/flour mixture and stir into the pot. Add the pearl onions and mushrooms then bring the pot to a simmer and cook for 10 minutes, until sauce has thickened.
7.Season to taste. Top with parsley and serve immediately.