Combine the paura tetepe (gelatine powder) and wai (cold water) in a small bowl. Stir and eave to bloom for 5 minutes.
Cut the tiakarete (chocolate) in to fine pieces. Add to a medium bowl.
Heat the miraka (milk) until just boiling. Remove from the heat and immediately pour it over the chopped tiakarete (chocolate). Stir it gently so that the chocolate melts completely.
Melt the gelatine mixture for 15 seconds in the microwave or over low heat on the stove. Pour it into the ranunga tiakarete (chocolate mixture) and stir until smooth. If it still has lumps, microwave the mixture for 10-15 seconds. Leave to the side to cool slightly. To a large bowl, add the kirīmi tīhi (cream cheese), puehu huka (icing sugar) and wanira (vanilla). Whip on medium speed for 2 minutes until smooth.
To a medium bowl, add the kirīmi (cream). Whip on medium speed until you achieve stiff peaks. Fold through the miraka tepe (yogurt) or kirīmi tepe (sour cream).
Add the cooled ranunga tiakarete (chocolate mixture) in to the cream cheese mixture in 4 parts. Stir gently with a whisk for 20 seconds after each addition.
Using a spatula, fold the kirīmi tāwhiuhwiu (whipped cream) in to the chocolate mixture in two parts. Once the mixture is smooth and well incoorporated, pour it into the chilled base. Chill for 8 hours. If you used the extra gelatine, it will be set in 6 hours.
Note: This will keep well in the fridge, in a sealed container for up to 5 days at this point. When you are ready to serve the keke tīhi (cheesecake), make the merenge Itariana (Italian meringue) up to 8 hours before serving. Any sooner than that and the meringue will loose its hold.