Mix coffee, 2/3 cup sugar and brandy (if using) until sugar is dissolved. Arrange half of ladyfingers in bottom of a 2 1/2 -quart serving dish; drizzle with half of coffee mixture.
Mix cream cheese, remaining 1/3 cup sugar and vanilla; beat until smooth. Add cream; beat until soft peaks form. Fold chocolate chips into mixture.
Spread half of cream cheese mixture evenly over ladyfingers. Top with remaining ladyfingers and drizzle with remaining coffee mixture. Spread remaining cream cheese mixture on top. Cover and chill for at least 2 hours, up to 24 hours.
Just before serving, sift cocoa over tiramisu. Spoon into bowls and serve.