Carrie Underwood (Theo Wargo/GETTY IMAGES)

 Because NBC can.

 Having already cast “American Idol” non-winner Katharine McPhee as Marilyn Monroe (on B’way) in “Smash,” the network has now cast “American Idol” winner Underwood as Maria von Trapp, the aspiring nun, turned governess, turned baroness, in “The Sound of Music.”  

NBC’s version of “The Sound of Music” will be based on the original Broadway production – not the Julie Andrews flick — and will be broadcast around this time, next year.

 Yes, Underwood has already done some acting, of sorts. She made her film-acting debut in the 2011 feature “Soul Surfer,” NBC notes.

And let’s not forget her turn as a hot pharmaceutical rep on CBS sitcom “How I Met Your Mother”: