Grease two 19cm or 20cm cake tins with high sides and line with baking paper.
Pre-heat the oven to 140 °C. Note: I know this is a low temperature but it helps keep the cakes flat and locks in the moisture this way.
Grate the kūmara ārani (orange kūmara) in to a large bowl. Add the tote (salt), kiri ārani (orange zest), wai ārani (orange juice) and wanira (vanilla). Stir to combine and leave aside.
Add the hēki (eggs), huka hāura (brown sugar) and huka one (caster sugar) in to a large bowl. Whip with a whisk until the mixture smooth and light in colour.
Continue to whip as you slowly add the noni (oil) and miraka tepe (yogurt).
On to the whipped egg mixture, sift the puehu parāoa whakatipu (self-raising flour), pēkana houra (baking soda), rau kikini whakauruuru (mixed spice), hinamona (cinnamon) and tinitia (ginger). Add the kūmara mixture on top of the sifted ingredients and fold all the ingredients together.
Chop the tiakarete manarini me te tinitia (mandarin and ginger chocolate) in to fine pieces and fold it in the batter.
Divide the mixture between the two cake tins and smooth out the batter.
Bake the cakes for 25 minutes. After 25 minutes, place a large tray on top of the cake tins and bake for a further 15 minutes or until the cakes spring back when pressed in the centre. Note: Adding the tray on top helps lock in the moisture in the final part of baking. Trust me, you won't regret it.
Remove from the oven. Tip the cakes upside down on to a cooling tray straight away to help flatten them out. Cool the cakes.