unforgettably       
adverb uk/ˌʌn.fəˈɡet.ə.bli/ us/ˌʌn.fɚˈɡet̬.ə.bli/
 难忘地;无法忘记地
in a way that has such a strong effect that you cannot forget it
  His descriptions are often unforgettably vivid.  他的描述常常生动到令人难忘。 
 These scenes are unforgettably horrible. 这些场景恐怖到令人难以忘怀。 
 See: unforgettable
 - More examples
 - His book ends, unforgettably, with the sound of the cathedral bells ringing.
 - She was one of the most unforgettably original figures on the international fashion scene.
 - Seeing your own words in print is unforgettably satisfying.