In the bowl of a 6-8 quart crockpot pot, add the chicken, onion, garlic, chili powder, oregano, paprika, thyme, allspice, crushed red pepper flakes, bay leaf, salt and pepper. Add the tomato paste, chicken broth and balsamic vinegar. Give everything a gentle stir to combine. Cover the crockpot and cook on low for 6-8 hours (or 4-6 hours on high) stirring once or twice if possible.
During the last 30 minutes of cooking, stir the broccoli rabe, roasted red peppers and cannellini beans together and add to the crockpot. Crank the heat up to high, cover and let cook 20-30 minutes longer.
Lightly shred the chicken with two forks; it should just fall apart. Stir in the parmesan and parsley.
Ladle the soup into bowls and serve with parmesan + crusty bread for dipping.
*If you prefer, you may add the broccoli rabe in the beginning of the cooking, but just know it will be cooked down a bit more. It’s still delicious this way, it just has a little less firmness to it.