For the Crust Layer:
In a food processor or blender, pulse the sunflower seeds until coarsely ground.
Add the hemp seeds, cacao powder, cinnamon, sea salt, and pitted dates. Blend until the mixture starts to come together when pressed.
If needed, add the maple syrup and blend again until the mixture sticks together.
Press the mixture tightly and evenly into the base of a 6-inch round cake tin with a removable base.
Place the crust in the fridge to chill while you prepare the other layers.
For the Chocolate Layer:
Finely chop the dark vegan chocolate and set it aside in a medium bowl.
In a small pot, heat the oat cream and stir in the agar flakes. Bring the mixture to a boil, then reduce to a simmer for 5-10 minutes, stirring frequently until the agar flakes dissolve.
Add the chopped chocolate to the pot and stir until melted. Mix in the maple syrup.
Carefully pour the chocolate mixture onto the crust layer and refrigerate for 15-30 minutes until set.
For the Raspberry Layer:
Place the raspberries and water in a small pot and bring to a boil. Simmer for 5-10 minutes until the raspberries break down into a mushy texture.
Press the raspberry mixture through a mesh sieve to remove seeds. Measure 1 cup (240 ml) of the strained raspberry liquid and return it to the pot.
Add the oat cream, maple syrup, and agar flakes to the pot. Stir well and bring the mixture to a boil, then simmer for 10-15 minutes, stirring frequently until the agar flakes dissolve.
Allow the mixture to cool before carefully pouring it over the set chocolate layer. Return the cake to the fridge to set for another 15-30 minutes.
To Serve:
Gently remove the cake from the cake tin and transfer it to a cake stand.
Top with fresh raspberries, seasonal berries, and chocolate shards for garnish.