For the blueberry syrup: A few hours ahead of time, place the frozen blueberries in a large jar, and cover with the sugar and 3 tablespoons of warm water. Place the jar in the fridge and let it rest for 4-6 hours or overnight to let the sugar draw some of the juices out of the blueberries. When it’s done resting, give it a good stir and add a bit more water if you want it less sweet. (For a faster option, you can muddle the blueberries after they thaw to speed up this process, or just melt them down in the microwave and use the purple blueberry juices that run off the thawed blueberries.) We’re just looking for some rich purple blueberry “syrup” here – nothing too fancy!

For the matcha: Heat 1/4 cup of water in a small jar with a lid. Add the matcha powder, cover, and shake until smooth.

Add the milk: Fill a large glass with ice. Pour the matcha over the ice, and then add the oat milk. If you want to preserve distinct color layers for Instagramability, pour the oat milk over the back of a spoon.

Finish with blueberry syrup: Finally, pour a tablespoon or two of the blueberry syrup into the glass and watch it sink to the bottom (more or less to taste, but this is a good amount to get the blueberry flavor in there without making it too sweet). Those green and purple layers are so pretty! Stir it up just before serving to get the blueberry flavor in each sip!