Grease a 16cm x 26cm rectangular slice pan; line base and long sides with baking paper, extending the paper 5cm over the sides.
Blend or process ¼ cup of the cashews, coconut flour, coconut oil and syrups until combined. Spread mixture into pan. Cover; refrigerate for 30 minutes or until set.
Meanwhile, blend or process remaining cashews with dates, extra oil, extra syrup, salt and essence until as smooth as possible. Spread date mixture over base. Cover; refrigerate for 30 minutes or until firmed slightly.
Make topping; Stir ingredients into a small bowl until smooth. Pour over date filling, spread to cover evenly. Cover; refrigerate overnight.