Spray the inside of a slow cooker with cooking spray and place the turkey breast into the cooker.
Mix the pepper, poultry seasoning, and garlic powder into the softened butter and rub half of it all over the turkey breast.
Carefully separate the skin from the meat over the breast and rub the rest of the butter mixture between the skin and meat.
Spoon the soup carefully over the turkey breast. Cover with the lid.
Cook on low for 6-7 hours or until a thermometer inserted into the thickest part of the breast registers 165° F.
Serve the sauce as gravy over potatoes, if desired.