Sift the butterfly pea powder into a small jar with an airtight lid.
Add the cold water to the jar, tightly close the lid, and shake the jar for about 30 seconds until no powder remains. (see note)
Add liquid sweetener, tightly close the lid again, and shake the jar a few more times until the sweetener is well-combined with the cold-brewed butterfly pea tea.
Slowly pour the blue matcha tea into a tall (16-ounce) glass.
Add several ice cubes, filling the glass.
Slowly pour the milk onto the ice cubes, being careful to preserve the matcha layer if you want a layered effect. Stir and enjoy!
Notes
For a purple latte, add 1 teaspoon of lemon juice before adding sweetener. Watch the color change from blue to purple!
Nutrition information will vary based on brands/substitutions used.