In a small saucepan, add heavy cream and tea bag. Bring it to simmer over medium-low heat, reduce heat to low and steep for 10 to 15 minutes. Gently squeeze tea bag with a spoon to get more flavor out.
Place white chocolate in a heatproof bowl and set bowl over a pan of simmering water. Pour Thai tea-infused cream through a fine strainer into chocolate. Slowly stir chocolate and tea-infused cream until completely melted. Remove from heat. Cover and chill in a refrigerator for 1 hour or until it's firm enough to scoop.
With a melon baller or small ice cream scoop, scoop dollops of chocolate mixture and place on a baking sheet lined with parchment paper. Chill in the refrigerator for 15 to 20 minutes.
Roll Thai tea truffles in powdered sugar and chill until ready to serve. Enjoy!