Pour 200 ml whole milk and 200 ml heavy cream into a saucepan and heat on medium while stirring. Once bubbles start to form around the edges (or it reaches 60 °C (140 °F)-70 °C (158 °F)) remove it from the heat.
Add 2 pasteurized egg yolk, 75 g sugar and 1 tsp cornstarch to a heatproof bowl and whisk until pale and smooth.
Temper the egg mixture by adding 1 ladle of hot milk/cream to the bowl while whisking.
Continue to whisk and gradually add the rest of the hot milk/cream.
Wipe the residue off the pan and then pour the mixture back in through a sieve.
Sift in 1 ½ tbsp matcha powder and then turn on the heat to low/medium low.
Whisk thoroughly until the matcha is incorporated.
Stir continuously using a silicone spatula and scrape the bottom to prevent burning. Once the mixture reaches a thick, custard-like consistency, remove from the heat.
Transfer it to a steel bowl placed in an ice bath. Stir for a few minutes to release some of the heat, then cover the surface with plastic wrap to prevent a skin forming on the top. Leave to cool for 10-20 minutes.
Once cool to the touch, transfer to a wide container with a lid and place in the freezer for 30 minutes. (Tip: It will freeze faster in a wide container rather than a tall one.)
After 30 minutes, take it out from the freezer and whisk for 1 minute. Return to the freezer and churn every 30-45 minutes for 3-4 hours. (Set a timer so you don't forget!)
If the mixture becomes too hard to whisk, switch to a spatula and make sure to scrape down the sides and mix them into the center.Once you've finished churning, freeze for about 2-3 hours. (It can take longer depending on the weather, the temperature of your freezer, and size of your container.) Remove from the freezer for 5-10 minutes before serving. (This will soften it slightly and make it easier to scoop.)
Enjoy!