Place the chicken breasts in a single layer in the slow cooker.
Sprinkle garlic powder, onion powder, and black pepper evenly over the chicken.
In a bowl, whisk together cream of chicken soup, gravy packets, and chicken broth until smooth.
Pour the gravy mixture over the chicken and add butter on top.
Cover and cook on low for 6 to 7 hours or on high for about 3 to 4 hours.
Shred the chicken directly in the slow cooker and stir until evenly coated with gravy.
Adjust consistency with additional broth if needed, then serve hot.