Place chicken breasts in a single layer at the bottom of your crockpot. For even cooking, ensure pieces are similar in thickness or pound thicker parts gently. If using larger breasts, consider cutting them in half horizontally to ensure they cook thoroughly and absorb more flavor.
Layer the sliced onions, minced garlic, chopped bell peppers, cherry tomatoes, olives, sun-dried tomatoes, and drained chickpeas over the chicken. The order matters here - placing the onions closest to the chicken helps them release their sweet flavors directly into the meat as they cook.
In a small bowl, combine the dried oregano, basil, thyme, cumin, paprika, red pepper flakes, salt, and pepper. Mix thoroughly with your fingertips to release the essential oils in the dried herbs, enhancing their aromatic qualities.
Whisk together the chicken broth, lemon juice, lemon zest, and tomato paste in a separate bowl until smooth.
Sprinkle the seasoning blend evenly over the vegetable layer, then drizzle with olive oil. Pour the sauce mixture over everything.
Cover the crockpot and cook on low for 7-8 hours or on high for 3-4 hours, until the chicken reaches an internal temperature of 165°F (74°C) and is tender enough to shred easily with two forks.
Once cooked, gently shred the chicken in the crockpot using two forks, allowing it to absorb the flavorful sauce. For a thicker sauce, remove the chicken first, then simmer the liquid on high (uncovered) for 15-20 minutes before returning the shredded chicken.
Garnish with fresh chopped parsley and crumbled feta cheese (if using). Serve with lemon wedges and your choice of base like rice, quinoa, or cauliflower rice.