In a microwave-safe bowl, heat 2 cups of heavy cream for about 1 minute until steaming but not boiling. Stir in 2 tablespoons of Thai tea mix, ensuring it is well combined. Cover and let it steep for 20 minutes.

Strain the tea-infused cream through a fine mesh sieve into a clean bowl. In another bowl, whisk together 1/2 cup of granulated sugar and 4 egg yolks until thick and smooth.

Slowly whisk in 1/4 cup of hot cream mixture into the egg yolks. Once incorporated, gradually add the egg mixture back into the remaining cream, stirring gently. Stir in 1 teaspoon of vanilla extract.

Pour the custard mixture into ramekins, filling each about three-quarters full. Place in a larger baking dish and pour hot water into the baking dish halfway up the sides of the ramekins. Bake for 35-40 minutes until set but slightly jiggly.

Remove ramekins from the water bath and cool at room temperature for 2 hours. Then refrigerate overnight. Before serving, sprinkle sugar on top and caramelize with a kitchen torch.