First blend the coconut milk, water, psyllium fiber husk and coconut sugar in a blender. Set aside.
Preheat oven to 200°C (top-/bottom heat). Line bottom of spring-form with baking paper and grease the sides lightly (I used coconut oil for this step).
Sift rice flour, cocoa powder and baking powder into a bowl and mix it. Add the coconut cream mixture and quickly stir to combine. Don't over stir.
Scoop the dough into the spring-form and spread it evenly.
Bake in oven covered* for approx. 35 to 45 minutes, or until an inserted wooden skewer comes out of the dough just slightly sticky. Let cool down a little before taking it out of the form. Then let cool down completely before applying the frosting.
For the frosting, blend all ingredients but the beetroot powder and cinnamon in a powerful mini-blender. It helps if the ingredients are at room temperature to stop the cacao butter from setting too early. Add a few tablespoons of water if necessary.
Once the mixture is blended to a smooth, creamy texture, add the beetroot powder and ground cinnamon and blend once more. If it is too hard to blend it, mix it manually instead of adding more water. Let cool down a little until the mixture gets a little thick.
If you'd like to make some decorative frosting dollops, take a few tablespoons of it aside. Spread the frosting evenly over the cake. Garnish with a little more beetroot powder if you wish. Transfer the remaining frosting into an icing bag to add dollops. Garnish with chopped pistachios if desired.
Chill for 1 to 2 hours until the frosting is set. Then keep covered until serving (the frosting tends to dry out after a while).