Make the matcha custard:

Cup of Yum
1. In a small glass bowl, whisk together the egg yolks, sugar, flour, cornstarch and matcha.
2. In a small saucepan, heat the coconut milk and whole milk over medium heat until scalding hot.
3. Gradually stream in the warmed milk while whisking the egg mixture (this is tempering the eggs so that they don't scramble).
4. Pour the warmed egg mixture back into the saucepan and place it on the heat. Continue to whisk over low heat until the custard thickens, about 2-3 minutes.
5. Remove from heat and stir in the vanilla extract. Transfer the custard to a bowl and place a piece of parchment paper over the top (to prevent a skin from forming).
6. Let cool, cover and chill in the fridge for at least 6 hours.

Make the bun dough:

1. In a large bowl, combine the flour, cornstarch, baking powder.
2. In a small bowl, add in the milk, water and sugar. Give it a stir. Heat (microwave) the mixture until lukewarm.
3. Add the yeast to the liquid mixture, give it a stir and let it become bubbly.
4. Pour the activated yeast mixture into the dry ingredients and knead the dough until it comes together.
5. Add in the oil and continue to knead until the dough becomes soft and shiny.
6. Cover the dough and let it rise in a warm location, about 40 minutes to 1 hour.
7. Roll the dough out into a log and divide the dough into 12 equal portions.
8. Flatten the dough into a circle, leaving the centre a little raised, and the edges thinner.
9. Remove the matcha custard from the fridge. Divide into 12 equal portions.
10. Place 1 heaped teaspoon of matcha custard in the centre of the dough, and pleat and pinch to seal the edges together.
11. Place onto a parchment-lined baking sheet.
12. Repeat with the remainder.
13. Preheat a flat griddle over medium heat.
14. Place the buns onto the griddle, spray the buns with a little water, cover with a lid and cook for 5-6 minutes until lightly golden brown on the bottom (you may need to adjust the heat). Flip and cook for another 3-4 minutes.
15. Best served warm or at room temperature.
16. Store the buns in an airtight container and place into the fridge for up to 3 days. Lightly warm before serving.