Start by greasing your slow cooker with a little butter or non-stick spray to prevent the chicken from sticking.
Place the 4 boneless skinless chicken breasts at the bottom of the slow cooker.
In a separate bowl, combine the Italian dressing mix, ½ cup lemon juice, ½ cup chicken stock, crushed garlic, and drained capers. Whisk until well combined.
Pour the prepared sauce over the chicken breasts evenly, ensuring they're well coated.
Cut the 2 tablespoons of butter into small pieces and scatter them on top of the chicken.
Cover the slow cooker and set it to low for 6-7 hours or high for 3-4 hours.
Once the chicken is cooked through and tender, carefully remove it from the slow cooker. Serve it with the sauce drizzled over the top.