Add all ingredients except butter to a bag and seal with a vacuum sealer or using the water displacement method.
Cook for 1 hour, up to four hours.
Remove from the water bath.
Heat 1 Tablespoon butter in a skillet over medium-high heat.
Reserve the sauce in the bag, and add the chicken breasts to the skillet. Sear chicken breasts 1-minute per side, tilting skillet and spooning butter over them as they cook. Set aside.
Pour the sauce into the skillet and cook until slightly thickened, 2-3 minutes. Remove from heat and stir in remaining Tablespoon butter.
Spoon the sauce over the chicken breasts and serve.