01 - Arrange the sliced onions, minced garlic, bell pepper strips, and halved cherry tomatoes evenly across the bottom of the slow cooker.
02 - Place the chicken breasts on top of the bed of vegetables in a single even layer.
03 - In a small mixing bowl, combine the balsamic vinegar, chicken broth, honey or maple syrup, Dijon mustard, dried oregano, dried basil, salt, and black pepper. Whisk until fully blended.
04 - Pour the balsamic mixture evenly over the chicken breasts and vegetables, ensuring everything is well coated.
05 - Cover the slow cooker and cook on the low setting for 4 to 6 hours, until the chicken reaches an internal temperature of 165°F and is fork-tender.
06 - Transfer the chicken and vegetables to serving plates, spoon the accumulated juices over the top, and finish with a sprinkling of fresh chopped parsley. Serve hot alongside rice, potatoes, or steamed vegetables.