Preheat oven to 160°C/325°F. Grease a deep 22cm (9-inch) square cake pan; line base and sides with baking paper, extending paper 5cm (2 inches) above sides of pan.
Stir chocolate and butter in a medium saucepan over low heat until smooth. Remove from heat; cool for 5 minutes.
Stir sugar into chocolate mixture; add egg and half the extract, stir to combine. Stir in sifted flours and cocoa until combined. Pour mixture into pan.
Combine cream cheese, extra sugar and remaining extract in a small bowl. Drop large spoonfuls of cream cheese mixture over chocolate mixture. Use a knife to gently swirl to create a marble pattern.
Bake for 1¼ hours or until a skewer inserted in the centre comes out clean. Cool brownie in pan before cutting into squares.