pre-heat the oven to 180C
use a sharp knife to make a pocket between the skin of the chicken and the breast on each side
fill each pocket with tarragon butter. For a crown, you will need around 20g of butter
use your fingers to spread the butter under the skin as much as possible
wipe the a roasting tray with olive oil and make a trivet with the shallots and carrots
put the crown onto the trivet, season well with salt and freshly ground pepper and drizzle with a little olive oil
put the roasting tray in the oven and cook for 10 minutes
baste well and reduce the heat to 170c.
continue to cook for 35mins, basting every 10 minutes or so
once the chicken has cooked, (internal temperature of 75C), remove it from the oven and put on a carving board, covered with a tent of foil to rest
put the trivet vegetables to one side (they are quite edible!)
put the roasting pan on the stove top and deglaze the pan over a high heat by adding the wine or vermouth to the pan and stirring briskly to incorporate all the juices
add a little water or stock, then reduce the mixture by about 50% to make a light tarragon jus.
serve the chicken sliced, with the vegetables on the side and jus poured over.