Classic roast chicken

Ingredients

• 40 grams butter
• 2 bacon rashers, finely chopped
• 1 small leek, thinly sliced
• 2 celery stalks, finely chopped
• 140 grams (2 cups) stale breadcrumbs
• 1 egg, lightly beaten
• 1 tablespoon roughly chopped sage leaves
• 1.8 kilograms corn fed whole chicken
• 2 tablespoons olive oil
• 1 kilogram (6) brushed potatoes, washed and halved
• 2 tablespoons plain flour
• 500 millilitres (2 cups) chicken stock