Prepare the chicken and the herb butter. Pat the chicken thoroughly dry with kitchen paper—this is non-negotiable for crisp skin. In a small bowl, mash the softened butter with the zest of one lemon, a tablespoon of chopped rosemary needles, a teaspoon of thyme leaves, and the minced sage. Season with half a teaspoon of salt and a pinch of pepper. The butter should look speckled and smell intensely herbal, almost like a savoury shortbread dough.

Season and stuff the cavity. Gently loosen the skin over the chicken breast by sliding your fingers underneath, taking care not to tear the membrane. Smear half the herb butter directly onto the flesh beneath the skin, then rub the remaining butter all over the outside of the bird. Sprinkle the remaining salt and pepper evenly over the skin, massaging it in so it adheres. Stuff the cavity with the quartered onion, the squeezed lemon halves (after juicing the zested lemon), the remaining herb sprigs, and the smashed garlic cloves. The cavity should look generously filled, almost bursting with aromatics.

Truss the bird (optional but helpful). Using kitchen string, tie the legs together crosswise and tuck the wing tips under the body. This creates a compact, even shape that cooks uniformly. The chicken should now look neat and symmetrical, ready for the oven.

Prepare the roasting pan. Scatter the chopped carrots and celery across the bottom of a large roasting tin, then pour in the chicken stock. Place a wire rack over the vegetables, or simply set the chicken directly on top of the veg. The liquid will steam and create a natural jus as it cooks, while the vegetables catch the delicious drippings.

Roast at a high temperature. Preheat your oven to 220°C (200°C fan) / 425°F. Place the chicken in the centre of the oven and roast for 20 minutes. You will hear a gentle sizzle as the butter hits the hot pan, and the skin will begin to tighten and turn a pale gold.

Lower the heat and baste. Reduce the oven temperature to 180°C (160°C fan) / 350°F. Using a spoon or baster, drizzle the pan juices over the chicken. Continue roasting for a further 50–60 minutes, basting every 20 minutes. The kitchen will fill with an intoxicating scent of lemon and herbs, and the skin will deepen to a rich, glossy amber. The chicken is ready when a thermometer inserted into the thickest part of the thigh reads 74°C / 165°F, or when the juices run clear when pierced with a skewer.

Rest before carving. Remove the chicken from the oven and tilt it slightly to allow the cavity juices to pour into the pan. Transfer the bird to a carving board, tent loosely with foil, and let it rest for at least 15 minutes. During this time, the internal temperature will continue to rise slightly, and the juices will redistribute throughout the meat. You will notice the skin relaxes subtly, becoming less taut but remaining beautifully crisp.

Make the pan jus (optional). While the chicken rests, place the roasting tin over a medium heat on the hob. Mash the softened vegetables into the pan juices with a wooden spoon, scraping up any browned bits. Simmer for 3–4 minutes, then strain through a fine sieve into a jug. The resulting jus should be rich, savoury, and just slightly thickened—a perfect companion to carve alongside each slice.