Prep the chicken: Pat the chicken dry with paper towels. This helps the seasoning stick and prevents a watery sauce.
Make the seasoning mix: In a small bowl, combine salt, black pepper, garlic powder, onion powder, thyme, and paprika. Zest one lemon directly over the bowl and stir in the olive oil or melted butter to create a loose paste.
Season generously: Rub the mixture all over the chicken, coating both sides.
Place a few thin lemon slices on the bottom of the slow cooker.
Add to the crockpot: Arrange the chicken on top of the lemon slices. Scatter minced garlic over the chicken, if using. Pour in the chicken broth and the juice of one lemon.
Set and cook: Cover and cook on Low for 3.5–5 hours or High for 2–3 hours, until the chicken is tender and reaches 165°F internally.
Breasts lean toward the shorter end; thighs can go a bit longer without drying out.
Optional quick sear: For extra flavor and a slight crust, remove the cooked chicken and quickly sear each side in a hot skillet with a little oil for 1–2 minutes.
Make a simple sauce: Transfer the cooking liquid to a small saucepan. Bring to a simmer. If you’d like it thicker, whisk 1 tablespoon cornstarch with 1 tablespoon cold water and stir into the simmering liquid.
Cook 1–2 minutes until glossy. Taste and adjust with more lemon juice, pepper, or salt as needed.
Finish and serve: Spoon the lemon-pepper sauce over the chicken. Garnish with chopped parsley and a few fresh lemon slices.
Serve with rice, mashed potatoes, roasted vegetables, or a green salad.