Combine onion, garlic, lemon peel and juice, rosemary, and thyme in your Crockpot® Slow Cooker. Add chicken and top with olives and butter. Cover and cook on LOW for 5 to 6 hours.
Remove chicken. Turn slow cooker to HIGH. Combine flour and water in a small bowl; whisk together and add to slow cooker. Cover and cook on HIGH for 10 to 15 minutes until sauce is thickened.