Add the matcha powder to a small bowl or cup. Pour the hot water over the matcha powder and whisk vigorously with a small whisk or fork for about 30 seconds until the powder is completely dissolved and no clumps remain. The mixture should be smooth and vibrant green with a slight foam on top.
Add the liquid cane sugar or simple syrup to the matcha mixture and stir well to combine. The sweetener should blend seamlessly into the matcha, creating a uniform sweet and earthy base. Let this mixture cool for about 1 minute if it's still very warm.
Fill a tall glass with ice cubes, filling it about three-quarters full. The ice should reach near the top of the glass to ensure your drink stays cold and refreshing throughout.
Pour the cold milk over the ice in the glass. The milk should fill the glass leaving about an inch of space at the top for the matcha mixture.
Pour the sweetened matcha mixture over the milk and ice. You'll see beautiful green swirls as the matcha cascades through the white milk, creating an Instagram-worthy layered effect.
Insert a straw and stir the drink thoroughly from bottom to top for about 10 seconds. The green matcha should blend completely with the milk, creating a uniform pale green color throughout the drink.
Taste your matcha latte and adjust sweetness if needed by adding more liquid sugar, stirring well after each addition. The flavor should be creamy, slightly sweet, with the distinctive earthy and grassy notes of matcha coming through.
Serve immediately while cold and enjoy your homemade Dunkin' style matcha iced latte. The drink is best consumed within 10 minutes before the ice dilutes the flavor too much.
