In a small bowl, whisk together lemon juice, chicken broth, minced garlic, olive oil, honey, oregano, salt, and pepper until honey dissolves. 2. Place chicken breasts in the slow cooker in a single layer. Pour the lemon mixture over the chicken, turning to coat each piece. 3. Cover and cook on LOW for 4 hours or HIGH for 2 hours, until chicken is tender and reaches 165°F internally. 4. Carefully remove chicken to a plate and tent with foil. 5. In a small bowl, mix cornstarch and cold water until smooth. Whisk this slurry into the liquid in the slow cooker. 6. Cover and cook on HIGH for 15-20 minutes, until sauce thickens to a light syrup consistency. 7. Return chicken to the slow cooker, spoon sauce over the top, and garnish with fresh parsley if desired. Serve warm.