In the bottom of your slow cooker, add the cream of chicken soup, dry gravy mix, water, garlic powder, onion powder, thyme, and pepper. Whisk it all together until it's smooth and no lumps remain. This base is what turns into that rich, velvety gravy later, so take an extra minute here.
Place the chicken breasts into the slow cooker and push them down so they're mostly submerged in the gravy mixture. I like to spoon a little of the sauce over the top too, so nothing dries out while it cooks. This helps the chicken stay tender the whole way through.
Put the lid on and set your slow cooker to low for 4 to 6 hours, or high for about 3 hours. I usually go with low heat because it gives a more tender, fall-apart texture. You'll know it's ready when the chicken shreds easily with a fork.
Carefully remove the chicken and place it on a cutting board or large plate. Using two forks, shred it into bite-sized pieces. I sometimes use a hand mixer for this step since it's faster and gives an even shred every time.
Add the shredded chicken back into the slow cooker and stir it through the gravy until every piece is coated. Let it sit for another 5 to 10 minutes on warm so the flavors settle together. This little rest makes a noticeable difference in taste.
Spoon the chicken and gravy over mashed potatoes, rice, or egg noodles while it's still hot. I like to add a sprinkle of fresh parsley or extra black pepper right before serving. It instantly makes the dish look and taste more finished.