1.Grease 20cm x 30cm (8-inch x 12-inch) rectangular pan; line base and long sides with baking paper, extending paper 5cm (2 inches) over sides.
2.Process biscuits and nuts until fine. Add butter; process until combined. Press mixture over base of pan. Refrigerate 30 minutes.
3.Beat cream cheese and rind in medium bowl with electric mixer until smooth. Add condensed milk and juice; beat until smooth. Pour cream cheese mixture over base. Refrigerate overnight before cutting.
Store squares in an airtight container in the fridge for up to 4 days.