Preheat oven to 350 degrees F/ 180 degrees C. Line a 7 inch/ 18 cm spring form pan with a circle of parchment paper. Grease well the pan.
In a small bowl combine flax seed meal and water. Mix well.
In a bowl combine coconut flour, baking powder and cinnamon. Whisk and set aside.
In a large mixing bowl whisk together xylitol and coconut oil. Add flax seed meal and egg and whisk again, until smooth.
Using a rubber spatula add the coconut flour mixture and mix well to combine. At the end add the cocoa powder, mixing gently with the spatula, until distributed evenly into the batter.
Transfer the batter to the prepared pan. Bake for about 25 minutes, or until the edges start becoming lighter and a toothpick, inserted in the center comes out clean.
Let the base cool for 30 minutes before spreading the filling on top.
Mousse:
Remove most of the liquid from the chilled coconut cream and use the solid part.
Combine all ingredients in a heatproof bowl. Place the bowl over a pan with gently simmering water (double boiler). Mix continuously until the mixture becomes smooth and liquid and all ingredients are combined.
Remove the bowl from the heat and let it cool for 5 minutes.
Place ice cubes into a large bowl. Place the bowl with the liquid filing on top and immediately start whisking energetically. Whisk until the mixture thickens and becomes fluffy.
Spread the filling on top of the brownie base, closed in the spring form pan. Cover the pan with aluminium foil and let it sit in the fridge for 6-8 hours.
Decorate with berries before serving.
Notes
Make sure the egg is at room temperature before adding it to the mixture as otherwise it would make the coconut oil harden.
For this cake a quality cocoa powder is very important as it creates the taste and the flavour of the dessert.
Store the cake for 3-4 days in the fridge, covered with aluminium foil.
Xylitol can be substituted with your low-carb sweetener by choice. For a high-carb version, you can use coconut sugar or maple syrup.