Preheat oven to 170C (fan-forced 150C, 325F, gas mark 3). Line the base and sides of a 6-inch round cake tin with non-stick baking paper.
Separate eggs. In a small bowl mix together the rice flour, cacao and tapioca flour. Beat egg whites on high for 2-3 minutes or until the whites are fluffy and stiff. Continuing to beat on high, add sugar in two batches, followed by egg yolks, one at a time. Beat for a further minute on high, the mixture should be thick and glossy. Reduce mixer speed to low and, in three swift batches, add the flour and cacao mixture and mix on low until just incorporated.
Pour mixture into the prepared tin and bake on the middle shelf of a preheated oven for 35-40 minutes, or until skewer comes out clean. Remove from oven and cool on a wire rack in the tin for 5 minutes, then gently lift the cake out and leave on a rack to cool completely (about 30 minutes). Once cooled, gently peel off the baking paper and using a serrated knife, cut the cake across into three even slices.
While the cake is cooling, prepare the chocolate cream filling. Finely chop chocolate and place in a small bowl. Add 1/8 cup cream and microwave for 20 seconds on high, then stir gently until the chocolate is melted and the mixture forms a glossy ganache (you can also do this in a small saucepan over very low heat, stirring to prevent the chocolate from burning, if you don’t want to use or don’t have a microwave).
Place remaining cream into a small bowl of a stand mixer, add vanilla essence and icing sugar. Beat on high until soft peaks. Reduce speed to medium and gradually add the ganache and allow to incorporate. Turn the speed up to high and beat until stiff (do not overbeat as the cream will turn into butter). Place in the fridge until ready to use.
In the meantime, make the salted caramel and sesame snap topping. Place rice syrup, coconut cream and sea salt flakes in a small saucepan set over low heat. Whisk together using a metal whisk. Bring to a boil, then simmer gently for a minute. Turn off the heat and allow the caramel to cool down before using (it will be very hot). If it sets, heat it again over low heat until warm and melted.
Crush sesame snaps.
To assemble the layer cake, place the bottom sponge layer on a serving plate. Top with half the chocolate cream and layer with another cake round. Repeat the process. Drizzle warm salted caramel sauce onto the cake and allow it to drip over the sides. Sprinkle the top with crushed sesame snaps.
Store, covered, in the fridge for up to 3 days. I found that a large Pyrex bowl fits perfectly over this size cake.