Start with the bread sauce; you can rush this, but it’s best if the milk and aromatics steep for an hour or so. Put the milk, two thirds of the butter, the cloves, bay leaves, onion, peppercorns, nutmeg and rosemary in a medium heavy bottomed saucepan. Bring almost to the boil, then reduce to a gentle simmer for 10 minutes. Remove from the heat and leave to infuse, ideally for 1 hour or more.
Later on (when the chicken is in the oven) strain the infused milk into a jug (discarding the aromatics), then pour all but 100ml or so of the milk into a clean pan. Bring to a gentle simmer, add the breadcrumbs and stir or whisk until incorporated. Turn the heat right down to the lowest setting and cook for 15 minutes until thickened, stirring occasionally. Add half a teaspoon of flaky salt, the cream and remaining butter and stir until incorporated. It should be the consistency of a loose porridge. Taste and season with salt and nutmeg.
To cook the chicken, 45 minutes before you want to eat, heat the oven to 200°C/Fan 180°C/Gas 6 and sprinkle salt generously over the skin of the legs/thighs. Place a heavy-bottomed, ovenproof sauté pan on a medium–high heat, add the tablespoon of sunflower oil, and, when it’s hot, place the chicken in, skin-side down. Cook for 10–12 minutes until the skin is crisp and golden.
Temporarily remove the chicken from the pan. Add the shallots and, a minute later the garlic, then a minute after that pour in the wine. Let the liquid bubble and reduce a little for 1 minute more, before stirring in the crème fraîche and adding half the tarragon sprigs. Distribute everything evenly then return the chicken to the pan, skin-side up this time. The liquid should come about halfway up the chicken and shouldn’t cover much of the crisp skin.
Cook in the middle of the oven for 25 minutes. Strip the leaves from the remaining tarragon sprigs and chop roughly. Then, just before serving, remove the pan from the oven and transfer the chicken to a warm dish. Return the sauté pan to the stove over a medium–high heat, and replace the tarragon sprigs with the chopped tarragon leaves.
Boil for 5 minutes until the sauce has reduced by a half, then remove from the heat, add the lemon juice, taste and season with salt, pepper and a tiny bit more lemon if required Serve the chicken on top of puddles of bread sauce, with the crème fraîche sauce spooned over the top, potatoes, and loads of green vegetables nearby.