Melt the butter in a frying pan, add the escalopes and fry gently for about 5 minutes turning once. Remove them and keep hot. Pour in the vermouth, stir and allow to bubble briskly until syrupy – it is important to reduce the mixture well. Add the cream and a few fresh chopped tarragon leaves. Cook for a few moments. Replace the veal escalopes in the pan and simmer very gently, shaking the ingredients so that they heat thoroughly. Serve hot.