Cut the chicken lengthwise and put it to marinate in a mixture of beer and soya sauce. Let it stand for an hour or so. Peel and slice the potatoes, put them in a greased tray and add 1 and 1/2 cups water, containing the previously dissolved sugar.
Season the potatoes with a little salt, pepper and dried basil. Put the chicken on top and add a few slices of butter evenly on it. Put the chicken to bake, topping it with the sauce from the potatoes from time to time to prevent burning.
Serve sprinkled with parsley.