Preparing the Chicken

Remove the chicken from the refrigerator 30 minutes before cooking to allow it to come to room temperature, ensuring even cooking.

Pat the chicken dry using paper towels; do not rinse. Trim any excess fat and discard the giblets if present.

In a small bowl, combine the brown sugar (or sweetener), mustard powder, garlic powder, and paprika. Evenly coat the chicken with the spice mixture, seasoning generously with salt and pepper.

Insert the halved lemon and rosemary sprig into the cavity of the chicken.

Preparing the Slow Cooker

Arrange the onions, celery, carrots, potatoes, and garlic at the bottom of the slow cooker to form a natural trivet. If omitting the vegetables, place a silicone rack or crumpled aluminum foil under the chicken to allow fat to drain.

Position the chicken on top of the vegetables or rack, ensuring it is elevated from direct contact with the cooker base.

Cover and cook on HIGH for 4-5 hours. Check at the 4-hour mark using a digital thermometer, ensuring the thickest part of the chicken registers 75°C (165°F). Alternatively, pierce the bird to confirm the juices run clear or slice into the thickest section to verify it is fully cooked.

If the chicken requires additional cooking, continue for another 15-20 minutes before rechecking.

Once done, carefully remove the chicken from the slow cooker, tilting it forward to drain any internal juices. Transfer to a roasting pan. Optionally, place the potatoes alongside the chicken.

Lightly mist the chicken with olive oil cooking spray and broil under high heat until the skin crisps to a golden finish.

Allow the chicken to rest for 20 minutes before carving.

Preparing the Gravy

Strain the remaining slow cooker juices through a sieve, discarding the onion, celery, and other solids.

Pour the strained liquid into a gravy separator, removing excess fat before transferring the remaining liquid to a saucepan.

Bring to a gentle simmer, adding additional chicken stock as needed to adjust volume.

Stir in the Worcestershire sauce and cornflour slurry. Simmer over low heat, stirring occasionally, until the gravy thickens.

Taste and adjust seasoning with salt and pepper as required.

Serving

Carve the chicken and serve with the reserved carrots, potatoes, and freshly prepared gravy.