In a medium saucepan, combine whole milk and jasmine green tea. Heat over medium until steaming, then steep for 10-15 minutes.

Strain the milk through a fine mesh sieve into a clean saucepan. Return to low-medium heat.

Stir in granulated sugar and salt until dissolved, heating for another 2-3 minutes.

Whisk egg yolks until smooth, then temper by adding a small amount of warm milk while whisking.

Return the tempered yolk mixture to the saucepan and cook over low heat until thickened, 170-175°F.

Remove from heat, stir in heavy cream and optional vanilla extract, letting it cool slightly.

Transfer custard to a bowl, cool for 15-20 minutes, then refrigerate for 4-6 hours or overnight.

Churn in an ice cream maker for 20-25 minutes until thickened to soft serve consistency.

Transfer to an airtight container, smoothing the top, and freeze for at least 2 hours before serving.