Soak the cashews in water for 4 hrs or overnight. Cut the banana into 2cm slices and arrange in a single layer on a parchment-lined plate. Freeze either overnight or at least 4 hrs before starting.

In a blender, whizz together the soaked and drained cashews, frozen bananas, dates, and vanilla seeds together until smooth and creamy, gradually adding the soy milk to bring the mixture together. Tip into an 18-20cm round springform cake tin. Freeze for at least 2 hrs.

For the berry layer, whizz together the blueberries, soy milk, dates, and walnuts until smooth in a blender. Carefully spread over the top of the vanilla nice cream cake layer and put in the freezer for 2-3 hrs or until set. Decorate the top with extra blueberries and some blackberries, if you like.