Servings: 4

whole chicken, about 1.5kg/3lb 5oz whole chicken, about 1.5kg/3lb 5oz
10g fresh tarragon leaves, plus extra to garnish 10g fresh tarragon leaves, plus extra to garnish
1 fennel bulb, trimmed and cut lengthways into pieces, fennel fronds separated and reserved 1 fennel bulb, trimmed and cut lengthways into pieces, fennel fronds separated and reserved
175g/6oz butter, softened, plus 50g/1¾oz, diced, for the sauce 175g/6oz butter, softened, plus 50g/1¾oz, diced, for the sauce
85g/3oz plain flour 85g/3oz plain flour
600ml/20fl oz chicken stock, plus extra if required 600ml/20fl oz chicken stock, plus extra if required
600ml/20fl oz white wine, plus extra if required 600ml/20fl oz white wine, plus extra if required
300g/10½oz baby king oyster mushrooms, trimmed (or king oyster mushrooms, chopped) 300g/10½oz baby king oyster mushrooms, trimmed (or king oyster mushrooms, chopped)
8 shallots, peeled and left whole 8 shallots, peeled and left whole
2 garlic cloves, peeled and left whole 2 garlic cloves, peeled and left whole
12 baby carrots, peeled 12 baby carrots, peeled
2 celery sticks, halved 2 celery sticks, halved
1 star anise 1 star anise
150ml/5fl oz double cream 150ml/5fl oz double cream
sea salt flakes and pepper sea salt flakes and pepper
mixed fresh herb leaves, such as flatleaf parsley and chervil, to garnish mixed fresh herb leaves, such as flatleaf parsley and chervil, to garnish
Romanesco florets, steamed, to serve Romanesco florets, steamed, to serve

Place the chicken on a board and, starting from just above the wishbone, lift the skin that runs along the breast of the bird. Stuff the tarragon and fennel fronds between the skin and breast, taking care not to split the skin.
Take a clean muslin cloth and cover it with a layer of softened butter. Dust the butter with some flour. Spread another layer of butter on top and dust again with the flour.
Place the chicken in the muslin and roll the cloth around the chicken to wrap it tightly. Tie the ends of the muslin with kitchen string.
Pour the stock and wine into a saucepan or flameproof casserole dish. Add the chicken, breast-side up, to the pan. It should be mostly submerged, so top up with stock or wine if necessary. Add the mushrooms, shallots, garlic, carrots, celery sticks, fennel pieces and star anise.
Bring to the boil and then reduce to a medium-low heat. Put a lid on the pan and simmer for 50 minutes. Turn off the heat, but leave the chicken sitting in the stock for another 20 minutes.
Drain the stock through a colander into a clean saucepan below, reserving the vegetables. Discard the garlic and star anise. Place the stock over a medium-high heat and simmer until reduced by at least two-thirds.
While the stock is reducing, untie the muslin and remove the chicken. Try to keep the flour and butter intact, which should have become pastry-like during cooking. Cover the chicken in foil to keep warm.
Scrape the flour and butter paste into a bowl and then whisk it slowly into the stock, until the sauce thickens. Season with salt and pepper and pass the sauce through a fine-mesh sieve into a saucepan. Add the cream and remaining 50g/1¾oz butter to the sauce and stir. Taste and adjust seasoning. Return the vegetables and mushrooms to the sauce and heat through.
Serve the chicken with the sauce alongside and garnish with the leaves. Serve the Romanesco in a separate bowl.