Rinse the bird’s cavity, season with salt and pepper and put the 6 sprigs of tarragon inside.
Combine the chopped tarragon, garlic and seasonings with the butter.
Working from the neck of the chicken with your fingers carefully loosen the skin from the breast to create a cavity on either side of the breast.
Work in the butter to cover both breasts.
Truss the bird with the string.
Dry the bird with kitchen paper and rub the skin all over with olive oil, salt and pepper.
Heat some olive oil in a roasting pan and carefully seal the bird on all sides.
Roast at 180C for 20mins on each breast and then 20mins on its back.
Remove from the oven and heat the brandy for a moment in a small saucepan, ignite with a match and pour over the bird.
Shake the pan until the flames die down and cover loosely with foil.
Leave the chicken for 15mins before carving.
Transfer the chicken to a warmed platter.
Scrape up the sediment in the roasting pan using a little water or white wine, add the chicken stock and cook for a minute or two to make a sauce.
Carve the chicken and serve.
A rice pilaf makes a good garnish along with a green salad.