Prep the slow cooker: Lightly grease the insert or use a liner. Pour the chicken broth into the bottom so there’s moisture right away.
Season the chicken: In a small bowl, mix salt, pepper, garlic powder, onion powder, paprika, and thyme. Pat the chicken breasts dry, rub with olive oil, then coat evenly with the seasoning blend.
Arrange in the cooker: Place the chicken in a single layer, overlapping as little as possible.
Add lemon juice or vinegar if using.
Cook low and slow: Cover and cook on Low for 2 ½ to 4 hours, depending on thickness. Start checking around 2 ½ hours. The chicken is done when it reaches 165°F in the thickest part.
Optional tenderness boost: Once it hits 160°F, turn off heat, keep covered, and let carryover cooking bring it to 165°F.
This helps keep juices inside.
Rest and slice: Transfer chicken to a plate and rest 5–10 minutes before slicing or shredding. Spoon a little cooking liquid over the top to keep it moist.
Use the juices: Strain the cooking liquid and save it. It makes a quick pan sauce or keeps leftovers juicy when reheating.