CREATE TABLE table_name_55 (date VARCHAR(255), outcome VARCHAR(255), opponent_in_the_final VARCHAR(255))
What is the Date that has a Outcome of winner, and çağla büyükakçay was the opponent in the final?
    
SQL: SELECT date FROM table_name_55 WHERE outcome = "winner" AND opponent_in_the_final = "çağla büyükakçay"