Add the water and matcha powder to a mason jar. Screw the lid on and shake vigorously until there are no chunks of matcha left.
Add the simple syrup and ice cubes, put the lid back on again, and shake.
Pour the cashew milk on top and stir.
Experiment around with your simple syrups! You might be surprised what goes well with the matcha (I've really liked cilantro and rosehip simple syrup the best so far).