Prep the slow cooker: Lightly grease the crock or use a liner. This helps prevent sticking and makes cleanup easier.
Season the chicken: Pat the chicken dry.
Sprinkle with lemon pepper seasoning, salt, black pepper, garlic, onion powder, and thyme on both sides. Set aside.
Build the flavor base: Add chicken broth, lemon zest, and lemon juice to the crock. Stir in the minced garlic if you didn’t use garlic powder.
Add butter (cut into small pieces) or drizzle in olive oil.
Add the chicken: Nestle the seasoned pieces in the liquid. If using sliced onion or carrots, tuck them around the chicken.
Cook low and slow: Cover and cook on Low for 3.5 to 5 hours or on High for 2 to 3 hours, until the chicken is cooked through and easily shreds or reaches 165°F internally. Thighs usually stay tender on the longer end.
Optional veggies late in the game: If adding quick-cooking veggies like green beans, stir them in during the last 30 to 45 minutes on Low so they stay crisp-tender.
Finish and taste: Adjust salt, pepper, and lemon to taste.
If you like extra brightness, add a squeeze of fresh lemon right at the end.
Make a quick sauce (optional): Transfer the chicken to a plate. Whisk 1 tablespoon cornstarch with 1 tablespoon cold water. Stir the slurry into the hot cooking liquid and cook on High for 10 to 15 minutes, until slightly thickened.
Spoon over chicken.
Serve: Garnish with chopped parsley and lemon slices. Great over rice, mashed potatoes, couscous, or a side of roasted vegetables.