4 hr 30
Put an upturned heatproof saucer in the slow cooker. (Check that the chicken will be able to sit on top of the saucer with the cooker lid in place.) Preheat the covered cooker on HIGH.
Mix together the butter, leaves from 3 of the thyme sprigs and the lemon zest and season with salt and pepper. Carefully ease your hand under the skin of the chicken, then gently lift the skin, taking car