Add the bacon to a large cast-iron skillet or high-sided sauté pan and place over medium heat. Cook until the bacon is crisp, about five to seven minutes, stirring occasionally. Remove the bacon from the pan leaving the rendered fat behind and set it aside. Add the mushrooms to the bacon fat, season with salt and pepper, and cook for three to four minutes or until golden and cooked down. Remove the mushrooms from the pan and set them aside with the bacon.
Add the butter into the pan along with the carrots, celery, and cocktail onions, season with salt and pepper, and cook for five to six minutes or until slightly softened and golden brown. Add in the garlic and deglaze the pan with the brandy. If using a gas stove, turn the heat off before adding the brandy to avoid accidental flare-ups. Allow the brandy to bubble away then sprinkle over the flour. Stir well to combine and allow the flour to toast for about 1 minute.
While stirring, slowly pour in the wine and one cup of chicken broth and bring to a low boil. Cook until the vegetables are tender and the sauce has thickened and reduced slightly.
Meanwhile, remove the legs from the rotisserie chicken along with the breasts.
Stir the cooked bacon and mushrooms into the sauce along with the parsley, thyme, and sour cream, adding more broth if needed, then nestle in the chicken, skin side up. Place a lid on the pan, reduce the heat to low, and cook just until the chicken is heated through, about two minutes if the chicken is still warm, 10 to 15 minutes if your chicken is fridge cold. Serve with crusty bread or on a bed of mashed potatoes for a hearty, quick, and fancy dinner. Enjoy!