Pre-heat the oven to 140 °CNote: I know this is a low temperature but trust me, if you bake a little lower, the cake will stay nice and moist with an even rise. Grease a 20 x 25 cm rectangle tin with 5cm high sides or a 23 cm cake tin and line it with baking paper.
Add the miraka (milk) and winika (vinegar) or wai rēmana (lemon juice) in to a jug. Give it a good stir and leave it aside to turn in to buttermilk.
Add the pata kūteretere (softened butter), huka hāura (brown sugar), puehu huka (icing sugar), tote (salt) and wanira (vanilla) to a large bowl. Tāwhiuwhiua mō te 5 mīniti - whip it (on high) for 5 minutes. You want this mixture to be light in colour and super fluffy. If not, whip for a couple more minutes.
Add a hēki (egg) at a time, whipping for 20 seconds after each egg.
Sift in half of the puehu parāoa (flour) and pour in half of the milk mix. Fold them gently in to the mixture until it has just combined.
Sift in the remaining puehu parāoa (flour), pēkana paura (baking powder), pēkana houra (baking soda) and the rest of the milk mix. Fold it all together again until smooth.
Pour it in to your prepared tin. Smooth out the mixture and then bake gently.
If you are baking it as a sheet cake it will take 40-45 minutes to bake. If you are using a cake tin it will take 45-55 minutes to bake. Check at the 45 minute mark. The cake is ready when it springs back in the middle when pressed. As it bakes, prepare the chocolate ganache so it is ready to add as soon as the cake has baked.