LOWCOUNTRY Vinegar Sauce: Mix vinegar, hot sauce, pepper and chili flakes in saucepan. Simmer on medium heat 30 min. Stir in barbecue sauce; cool. Refrigerate until ready to use.
CHICKEN Biscuit: Combine chicken, broth and barbecue sauce in large pot. Bring to low simmer. Cook 1 hour or until chicken is tender; cool. Cover and refrigerate overnight.
REMOVE chicken from liquid, pull meat from bones and shred; discard liquid and bones. Add Lowcountry Vinegar Sauce; mix until well coated. Reheat mixture to 165ºF.
FOR each serving: Fill 1 biscuit with 1/4 cup each collard greens and kale and 5 oz. chicken mixture.