The night before making this, place the can of coconut milk in the fridge. Line the base and sides of a 23 cm (9 inch) spring-form or loose-bottomed cake tin with baking parchment.
Soak the cashew nuts in 300 ml of filtered water with ½ tsp of Himalayan pink salt for 3–4 hours.
To make the base, in a food processor chop up the dates with the salt and vanilla seeds to form a ball-like paste. Add the coconut and hemp seeds and blitz to combine. Melt the coconut oil, add to the mix and process until everything is combined. Turn out into the prepared tin and press down to form an even base. Refrigerate.
In a blender, process 150 g of the blueberries, the lemon zest and juice, honey and salt to form a purple juice. Drain and rinse the cashew nuts thoroughly, then add them to the blueberry juice and process until smooth.
Open the can of coconut milk and remove the cream on the top, which will have set overnight. You need 240 g, so use some of the thinner milk from the bottom of the can if necessary. Whip up the coconut cream in a freestanding mixer or using an electric whisk, until smooth and thick.
Melt the coconut oil and blend it into the blueberry juice and then add everything in the blender to the whipped coconut cream. Lightly whisk everything once more until just combined. If you overmix, the cake won’t be as light as it should be. Fold in the remaining 175 g of blueberries then pour the mix over the prepared base. Refrigerate for about 2 hours until firm.
When set, 'de-mould'. Decorate with blueberries and scented edible flowers. Serve immediately. Keeps well in the fridge for up to five days.