Add the kirīmi (cream) and miraka (milk) in to a large pot. Heat it up gently over low heat until just simmering.
As the cream mixture heats, add the hēki (eggs), tote (salt), huka one (caster sugar), puehu kahitete (custard powder), kiri rēmana (lemon zest) and wai rēmana (lemon juice) in to a large bowl. Stir it all together until smooth.
Remove the cream mixture from the heat. Stir continuously as you slowly add the warm cream it to the egg mixture. Add a little at a time.
Pour all the mixture back in to the pot and place over low-medium heat. Stir constantly until the kahitete (custard) is smooth and thick.
Pour all of the custard in to a bowl, add the cubed pata (butter) and the wanira (vanilla). Stir well until smooth.
Cover the kahitete (custard) with baking paper to stop a skin from forming. Refrigerate for 30 minutes or until you are ready to use it. This will keep for up to 5 days in the fridge.
Once you are ready to use it, stir the custard well until it is smooth. Fold through the kirīmi kukū (thickened cream) and it is ready to go. You can pipe it like I have or simply spread it on with a butter knife.