Pre-heat the oven to 150 °C, bake setting or 130 °C, fan bake. Grease two 20 cm cake tins and line with baking paper. Add the kākano chia (chia seeds) to a small bowl. Pour over the wai mātao (cold water) and stir it. Leave aside for the chia to absorb the wai (water).
Add the miraka pīni (soy milk) and winika (vinegar) to a medium bowl. Give it a good stir. Leave it aside for the miraka (milk) to turn in to miraka pata (buttermilk).
Cut the tiakarete parauri (dark chocolate) in to fine pieces and add it to a small bowl. Add the kōkō (cocoa) and wai wera (hot water) on top of the tiakarete (chocolate) and stir until it is all melted. Add in the huka one (caster sugar) and stir again. Leave aside.
To a large bowl, sift in the puehu parāoa (flour), pēkana paura (baking powder), pēkana houra (baking soda), tote (salt) and huka hāura (brown sugar).
Make a well in the centre and add in the raununga tiakarete (chocolate mixture). Fold it in until roughly combined.
Add the wanira (vanilla), noni (oil) and chia mixture in to the soy milk mixture. Stir it until well combined and pour it in to the chocolate mix a third at a time, folding well after each addition.
Divide the mixture between the two prepared cake tins. Bake for 25-30 minutes until they spring back in the middle of the cake when pressed.
Leave for five minutes in the tin and then flip them straight on to cooling racks. Leave the baking paper on as they cool to help lock in the moisture.