Drain tomatoes, reserving 1/2 cup juice Combine tomatoes, tomato juice, raisins, cocoa, peanut butter, chili powder, garlic, 1/2 tsp salt, 1/2 tsp pepper in slow cooker. Season chicken with salt and pepper and nestle into slow cooker. Cover and cook until chicken is tender, 4 to 5 hours on low Transfer chicken to serving dish. Process braising liquid in blender until smooth, about 20 seconds. Season sauce with salt and pepper to taste, pour over chicken and sprinkle with cilantro. Serve with rice, such as cilantro rice.