Note: If using fresh pearl onions, cut the root and stem ends, plunge into boiling water for 1 minute and then shock in ice water. When cool, peel the outer skin.
In a large saucepan, place the wine (reserve 1 T.), broth, parsley sprigs, thyme and bay leaf. Bring to a simmer and cook for about 25 minutes or until reduced to about 3 cups.
While the sauce is simmering, brown the bacon in a Dutch Oven, about 8 minutes. With a slotted spoon, transfer the bacon to a paper-towel-lined plate. Reserve 2 T. fat in a small bowl and discard the rest.
Season the chicken with salt and pepper and a little Greek Seasoning.
Add 1 T. of the reserved fat to the Dutch oven and heat until just smoking. Add 1/2 the chicken in a single layer and lightly brown for about 2 minutes per side. Transfer chicken to a plate and repeat this step with the remaining chicken and fat.
Melt 3 T. butter in now-empty Dutch oven over medium heat. When foaming subsides add the onions and mushrooms and cook about 7 minutes until lightly browned. Add garlic, tomato paste and flour and cook about 1 minute.
Remove the bay leaf.Add the reduced wine mixture to the Dutch oven, scraping the bottom to loosen the chicken bits and add 1/4 t. pepper.
At this point return the chicken and bacon to the Dutch oven and bring to boil over high heat. Then, reduce heat, cover pot and simmer for 25 minutes or until chicken is tender. Stir occasionally.
Transfer chicken to large bowl and tent with foil. Increase heat and simmer sauce until thick, about 5 minutes.
Remove Dutch oven from heat and stir in 2 T. butter and 1 T. wine. Add a little salt, return chicken to the pot and sprinkle with the minced parsley. Serve immediately over mashed potatoes.