In a medium saucepan, combine the Thai tea mix, whole milk, and ½ cup of heavy cream. Heat over medium-low until steaming and vibrant orange, about 5–7 minutes.

Pour the steeped mixture through a fine mesh sieve into a large bowl to eliminate tea leaves.

Add sweetened condensed milk and vanilla extract to the strained tea mixture, stirring until smooth.

In a chilled mixing bowl, whip the remaining heavy cream until stiff peaks form, about 3–5 minutes.

Gradually fold the whipped cream into the Thai tea mixture in two to three batches.

Transfer to a freezer-safe container, cover tightly, and freeze for a minimum of 8 hours.

Before serving, let the ice cream sit at room temperature for 10–15 minutes to soften slightly.