Soak cashews in water overnight.
Blend the base ingredients together then press down in your square tin lined with baking paper.
Drain and rinse your cashews and blend in your food processor with the other mousse layer ingredients until smooth and creamy.
Layer the cacao mousse on top of the base and leave to set in the freezer for 2-3 hours.
Top with melted chocolate, berries and buckwheat.
Store in the fridge or freezer.