Preheat the oven to 180°C (160°C fan).

Heat a good drizzle of olive oil in a large ovenproof casserole dish over medium heat. Add the onion and leek and cook for 5–6 minutes until softened. Stir in the garlic and cook for a further minute.

Pat the chicken dry and season all over with salt, pepper and the mixed herbs. Cut the lemon in half and place it inside the cavity.

Nestle the chicken into the pot with the vegetables and pour in the chicken stock. Cover (with a lid or foil) and roast for 1 hour to 1 hour 15 minutes, until the chicken is pretty much cooked through.

Remove the pot from the oven and stir in one tin of cannellini beans (left whole) and the orzo around the chicken. Drizzle a little olive oil on the chicken to encourage it to turn brown and return to the oven, uncovered. Cook for 15-20 minutes until the orzo is tender and the chicken is gorgeously golden.

Remove the chicken from the pot and set aside to rest. Blend up the second tin of beans until smooth, (or roughly mash up with a fork as well as you can). Stir the creamy beans into the broth along with the Dijon mustard and double cream (if using). Add the chopped tarragon, season generously with salt and pepper.

Carve the chicken and serve on top of a bed of creamy beans. Top with flakey salt, black pepper and more fresh tarragon leaves. Or you could shred the chicken and stir it back into the pot for a more rustic, stew-like version.

The video below will help with this recipe although don't add the oil to the chicken at the start- it doesn't need it.