Preheat the oven to 180 C / 356 F fan-forced.
Grease the bottom of a 20 cm / 8 inch round cake tin with the 1/2 tsp of oil and leave it in the oven to heat up.
In a bowl, add the coconut cream and salt. If making the pandan version then add pandan extract and white caster sugar to the mixture. If making the brown sugar version then add the vanilla extract and brown sugar to the mixture.Put into the microwave for 1 minute, then mix until combined. Add the tbsp of canola oil and set aside.
In another bowl, crack the eggs. With a pair of scissors, cut the egg yolks into small pieces. Add the eggs into the bowl with the coconut mixture.
Sift half of the tapioca starch and rice flour into the egg mixture and gently whisk while keeping the whisk touching the bottom of the bowl at all times. After about a minute, add the remaining tapioca starch and flour and continue whisking for another minute.
Sift the cream of tartar and bicarb soda into the mixture. Mix for roughly 30 seconds.
Take the cake tin out of the oven and place it on a heat-proof surface.
Press the cake mixture through a sieve and into the hot cake tin. Grab your oven mitts or a thick tea towel, and drop the cake tin from a height of roughly 2 cm onto your work surface a few times to get the air bubbles out.
Put the cake into the oven and bake for 40 minutes.
Set up a cooling station by placing a cooling rack on a couple of mugs, or something else that will give the cooling rack some height. See picture above to see what I mean. This is to allow plenty of air to circulate under the cake to reduce any condensation as it cools upside down.
After 40 minutes, take the cake out of the oven and immediately rest it upside down on the cooling station.
After about 45 minutes of cooling, or once the cake feels lukewarm, remove from the tin and serve.