Heat a Dutch Oven or large oven-safe pan with a lid over medium heat. Pat chicken dry and sprinkle evenly with ¼ teaspoon salt and ¼ teaspoon pepper. Add oil to the skillet and swirl to coat.
Brown chicken on both sides. In a large pan, you can brown all of the chicken at one time. In a Dutch Oven, you will need to brown the chicken in two batches. Set chicken aside.
Add onion, carrot, celery, and garlic to the pan. Cook for 6 minutes, stirring occasionally.
Add the wine and cook for 2 minutes, scraping the pan to loosen the brown bits. Add the chicken back to the pan.
Combine stock and flour in a bowl, stirring with a whisk until smooth. Add stock mixture to pan.
Stir in tarragon, 2 tablespoons parsley, mustard, and bay leaf and bring to boil. Cover. Transfer to the oven and bake at 325° for 45 minutes or until chicken is cooked through and very tender.
Remove dish from oven and remove chicken from pan. Top with ¼ cup cooking liquid. Keep warm.
Heat pan over medium-high heat and bring to a boil. Boil for 5 minutes or until the mixture is reduced to 3 cups.
Whisk in the butter, remaining ¼ teaspoon salt, and remaining ¼ teaspoon pepper. Discard bay leaf.
While the sauce is reducing, preheat the broiler on high. Toss tomatoes with a teaspoon of olive oil and arrange in a single layer on a jelly-roll pan. Broil for 6 minutes or until blistered. Sprinkle chicken with tomatoes, crumbled bacon, and remaining 1 tablespoon of chopped parsley.
Serve with sauce.
Notes
Technique - Be sure to adequately reduce your sauce. The sauce reduction process intensifies the flavors of the dish and creates a velvety texture that coats the chicken. Be patient while the pan sauce reduces and allow it time to reach the correct consistency.Variations - Creamy: To make a creamy chicken in wine sauce, add heavy cream to the sauce. I would not place this cream sauce in the oven as it can break, so cook the cream sauce separately on the stovetop.Storage -Store leftover chicken in the fridge in an airtight container. It will remain good for 3-4 days. You can also freeze this dish for about 3 months.