Place the chicken in a deep skillet or pot with the onion, celery, carrot, and bay leaves. Cover with just enough water to come to the top of the meat. Bring to a boil, reduce the heat, and then simmer until cooked through, about 12 to 15 minutes. Remove the chicken to a plate with tongs and tent with foil. Strain the poaching liquid and reserve 1 cup.
Return the skillet to medium heat and add the butter to melt. Add the shallot and garlic and stir for 2 minutes. Sprinkle in the flour and stir another minute. Stir in the thyme and wine. Add lemon zest and juice, the reserved poaching liquid, and simmer to reduce the sauce and thicken a bit. Stir in the cream, if desired. Slice the chicken and add to the sauce to warm. Serve with bread or a simple pasta dish such as Egg Pasta with Leeks. Garnish with basil and serve.