Add a small amount of the warm coconut milk to the cocoa mixture and whisk until a smooth slurry forms.
Use a spatula to transfer the cocoa mixture back into the pan with the rest of the coconut milk and stir.
Cook on medium-low heat for about 5 minutes, whisking regularly, until the mixture thickens. It should be thick enough to cling to the whisk, but it will continue to thicken to pudding consistency as it cools.
Divide into serving dishes and place in the fridge to chill for at least 1 hour. To prevent a skin from forming, you can cover the surface of the pudding with plastic wrap.
Serve with toppings of your choice such as berries, shredded coconut, whipped coconut cream or grated dark chocolate.
Notes
When measuring make sure to use level measurements, not heaped spoonfuls for best results.