For the crust, in a high-speed blender or food processor, pulse the sunflower seeds to fine crumbles and transfer to a medium sized bowl. Pulse dates to fine crumbles and add to bowl.
Sift in cacao or cocoa powder, add water and mix well.
Line cake spring-form with baking paper. Scoop dough for the crust into spring-form and spread it evenly, pressing it gently smooth.
For the first chocolate layer, blend all ingredients until smooth. I find it helps to start with a few pulses until the mixture starts moving. Start with 1 1/4 cup water and add more only if needed.
Pour the mixture into the cake tin. Spread evenly. Place in freezer while preparing the next layer.
For the top chocolate layer, blend all ingredients until smooth. Take cake tin out of freezer and pour the mixture on top, spread evenly.
Add garnish of your choice (I used freeze-dried raspberries and shredded coconut).
Place in freezer until set (approx. 6 hours). Cut slices when it is just soft enough, this way you’ll get nice and clean edges. For best results, let defrost in fridge to achieve a consistent smooth and silky texture.