Gather the ingredients.

In a small bowl, whisk hot water and matcha tea powder together and set aside.

Place the egg yolks in a medium-size saucepan, lightly whisk the egg yolks. Note: Do not heat the pan yet.

Add sugar in the pan, and mix the sugar with egg yolks until well incorporated.

Gradually add milk to the egg and sugar mixture and mix well.

Place the pan on low heat and heat the egg mixture, stirring constantly to make sure it doesn't burn.

When the mixture thickens slightly, remove the pan from the heat and soak the bottom of the pan in ice water to help cool the egg mixture.

Add the matcha powder and water mixture into the egg mixture and mix well. Continue to cool the mixture in ice water.

Whip the heavy cream so that it is slightly thick and airy.

Add this whipped heavy cream into the egg and matcha mixture. Gently incorporate all the ingredients using a spatula, until mixed.

Pour the ice cream mixture into an ice-cream maker and follow your ice-cream maker instructions for churning.

Then pour the mixture into a freezer-safe container with lid, and freeze for 8 hours or longer before serving.