Washington : Kristen Stewart became the first American actress to win a Cesar Award after grabbing the Best Supporting Actress award for ‘Clouds of Sils Maria’. The movie was written and directed by Olivier Assayas’s starring Juliette Binoche and Chloe Grace Moretz in the lead roles, Deadline.com reported. It was also a big night for Oscar nominated ‘Timbuktu’ as it swept seven awards of the eight categories including Best Film, Best Original Screenplay,Best Sound and Best Score. Cesar Awards are known as the French Oscars.