Cut the lemon in half, then continue cutting one of the halves into round slices.
Place the chicken in the Dutch oven, then place the full half lemon inside the chicken. Gently place your hand between the chicken meat on the skin to detach it. Place the lemon slices on top of the chicken yet under the skin, then similarly add the thyme and butter.
Sprinkle the chicken with salt and pepper.
Bring the Dutch oven to about 350 degrees F (180 degrees C) then cook for about 1 hour, or until the chicken is cooked throughout, at least 165 degrees F (74 degrees C).