In a medium saucepan, combine Thai tea mix, whole milk, and ½ cup of heavy cream. Heat over medium-low until steaming, about 5–7 minutes. Remove from heat and steep for another 5 minutes.

Using a fine mesh sieve, strain the steeped tea mixture to remove the tea leaves. Discard the solids and let the liquid cool.

Whisk in sweetened condensed milk and vanilla extract into the cooled tea mixture until smooth.

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

Gently fold the whipped cream into the tea mixture in 2–3 batches, being careful not to deflate the whipped cream.

Pour the mixture into a prepared loaf pan and smooth the top. Cover tightly and freeze for at least 8 hours.

Before serving, let the ice cream sit at room temperature for 10–15 minutes for easier scooping. Serve with toasted coconut flakes.