Preheat oven to 350*. Wrap chicken in foil, and cook in oven until thoroughly done. Wash and drain broccoli, cook in boiling salted water for 10 minutes. Melt butter in saucepan, blend with flour and gradually add chicken stock. Cook over low flame for 10 minutes, stirring frequently. Fold whipped cream and sherry into sauce. Add salt and pepper. Place broccoli in 9 X 13 pan, pour half of the sauce on top. Mix Parmesan with remaining sauce. Now place chicken on top and cover with remaining sauce. Cook in over until sauce bubbles and is lightly brown (30-45 minutes). Enjoy!