Sprinkle chicken with a little garlic powder, salt and pepper. Place in crock-pot.
In a small microwave-safe bowl or plate, add onions. Cook for 1-2 minutes until soft. Add onions all over chicken.
In a small bowl, mix together maple syrup, Dijon, balsamic vinegar, garlic, and olive oil. Whisk until smooth. Pour over chicken and onions. Using a spoon, cover chicken all over with sauce.
Set crock-pot to HIGH heat and cook 2½– 3 hours or set on LOW heat and cook 5-6 hours until chicken is cooked through and tender. Cook time varies due to the type of crock-pot you have.
Cool chicken slightly and shred. Use your hands or a fork to shred.
When ready to serve, place shredded cabbage or broccoli slaw in a microwave-safe, large bowl. Cook in microwave for about 2 minutes, until soft.
To serve: add 1¼ cup cooked cabbage to each plate. Add 1 cup shredded chicken with sauce.