Preheat oven to 180 celsius. Grease a 8"tart pan. Set aside.
In a food processor, combine crust ingredients
and pulse to combined. You should get a moist mixture than can be easily moulded. Firmly press into bottom and up the sides of tart tin. Bake for 20-25 minutes until crust is golden brown. Transfer to a wire rack and let it cool while you're preparing the filling.
Put the blackberries and 2 tbsp of water into a saucepan over a medium heat. Mash the blackberries as they begin to heat up. Strain it through a fine mesh sieve. Allow to cool.
Add white chocolate, coconut cream into a saucepan and place on the stove on low heat. When the mixture becomes warm and the white chocolate has melted, add the agar-agar, supercolour powder and maple syrup. Stirring constantly, cook until agar completely dissolve.
In a food processor, add the white chocolate-coconut cream, blackberry mixture, soaked cashew nuts. Process until smooth. Pour the filling into the crust. Place tart in the fridge overnight to set. Garnish and enjoy!