Season chicken breasts with salt and pepper.
In a small bowl, whisk together balsamic vinegar, chicken broth, brown sugar and garlic; set aside.
Mix together the basil, oregano, thyme, rosemary, parsley, red pepper flakes, salt and pepper, to taste .
Place chicken breasts into a 6-qt crock pot, season with her mixture, and then stir in balsamic vinegar mixture.
Cover and cook on low heat for 6-7 hours or high for 3-4 hours.
Serve immediately, garnished with parsley, if desired.