Saute onion in a small amount of oil. When onions are transparent, add cream cheese and cubed chicken. Stir until cheese is softened and well mixed. Put about 1/4 to 1/2 c. of chicken mixture on each flour tortilla and roll. Place in a greased casserole dish. Generously cover rolled enchiladas with grated cheese. Pour whipping cream over enchiladas and cover with aluminum foil. Bake at 325* for 30 minutes.