Preheat oven to 375 F. In an ovenproof skillet, heat 1 tablespoon of the oil under medium to high heat. Season the chicken with salt and pepper and add it to the skillet. Cook until browned all over, about 8 to 10 minutes, flipping once in between. When chicken is browned, transfer it to a plate and set aside.
Add the bacon to the skillet and cook until fat is rendered, about 2 minutes. Drain off the fat and add remaining oil to skillet. Stir in flour until incorporated. Add the onion and garlic. Cook until soft and translucent, about 3 to 5 minutes. Add the tomato and tomato paste and cook until tomato is somewhat soft, about 5 more minutes. Add the milk and broth and bring mixture to a boil. Stir until it begins to slightly thicken, about 3 to 5 minutes. Return the chicken and any juices to skillet. Stir in parsley sprigs as well.
Cover the skillet and braise the chicken in the oven for about 20 minutes, or until cooked all the way through. You can't really go wrong with chicken thighs because as long as you don't burn it (which is practically impossible in a braising situation), then you can't dry it out, or cook it "too long".
Carefully take skillet out of oven with an oven mitt and remove chicken and place on a platter. Then, STILL wearing oven mitt, (I say this because I damn near burnt myself by grabbing onto the skillet handle without one), place skillet under moderate heat and stir mixture until smooth, about 2 to 4 minutes. Stir in the remaining chopped parsley and spoon the gravy onto the chicken.