Casserole Roast Chicken with Tarragon

There are two kinds of tarragon, French and Russian, but we prefer to use French in this recipe because it has a better flavour than the Russian variety. Unfortunately French tarragon is more difficult to come by than Russian because it is propagated by root cuttings: you can’t just grow it from seed like the Russian tarragon. French tarragon grows to a height of about 23cm, whereas the Russian will grow to about 1.25m in the summer.