SCHEMA:
CREATE TABLE table_name_55 (date VARCHAR, outcome VARCHAR, opponent_in_the_final VARCHAR)
USER:
What is the Date that has a Outcome of winner, and çağla büyükakçay was the opponent in the final?

QUERY:
SELECT date FROM table_name_55 WHERE outcome = "winner" AND opponent_in_the_final = "çağla büyükakçay"