To buy boneless chicken breasts with the skin on, purchase chicken breasts on the bone and ask your butcher or supermarket to remove the bones but leave the skin intact. It is a much more beautiful presentation and it keeps the chicken moist. Bones can be used to make stock or discarded.
If you prefer, or can only obtain skinless chicken, then make a cut on the bottom of each breast the length of the breast to form a pocket. Stuff each breast with same amount of filling and turn slit side down. Brush top with a film of Dijon mustard and continue with recipe.
To heighten mushroom flavour, add one 10g package of soaked dried mushrooms along with the regular mushrooms, if desired.
Dried currents may be substituted for cranberries.
Trim chicken breasts of any fat. Heat butter in skillet on medium high heat. Add onion, saute until softened the add mushrooms and zucchini. Saute until all liquid has evaporated, stirring occasionally, about 10 minutes. Stir in tarragon and cream. Continue to cook until cream has reduced and mixture is thick, about 5 minutes. Stir in lemon juice and add enough breadcrumbs to hold mixture together. Add parsely and season well with salt and pepper. Season chicken breasts with salt and pepper.
With fingertips, make a pocket between skin and flesh of each chicken breast. Stuff about 1/3 c filling under skin, tucking skin around breast to enclose stuffing. Place chicken breasts in large oiled (preferably metal) baking dish or roasting pan. Dot with butter, refrigerate until one hour before baking.
Baking in 400F (200C) oven for 30 to 40 minutes or until juices run clear. If skin is not quite crisp enough, place under broiler to crisp it.
While chicken is baking, place sauce ingredients in pot and bring to boil over medium high heat. Reduce by half, skimming occasionally, about 25 minutes. Over low heat, whisk in butter, 1 tb at a time, until sauce is slightly thickened and glossy. Just before serving, skim any fat off pan juices and add juices to sauce.
Either slice chicken breasts into 1/4 inch slices before serving and coat with sauce or serve chicken breasts whole and place sauce in sauce boat. Garnish with extra dried cranberries, if desired.