Season the chicken breasts on both sides with garlic powder, salt, and black pepper.
In the slow cooker, whisk together the water (or broth), gravy mix, cream of chicken soup, garlic powder, paprika, and remaining salt and pepper until smooth.
Place the seasoned chicken into the slow cooker and flip to fully coat with the gravy mixture.
Cover and cook on low for 4 to 5 hours, or until the chicken is cooked through and tender.
Remove the chicken and shred or slice it as preferred.
Stir the sour cream into the gravy in the slow cooker until smooth and creamy.
Return the chicken to the slow cooker or serve the gravy spooned over the chicken.
Serve hot over mashed potatoes, rice, noodles, or even thick-cut toast.