Make 1 shot of espresso using 1/2 cup hot water and the espresso. I like using a Moka pot! Stir in the maple syrup and salt. Cool to room temperature, then refrigerate until cold.
In a small bowl or cup, whisk the remaining 1/2 cup hot water with the matcha until dissolved. Make sure it's well combined, since you don't want a powdery drink. Cool to room temperature.
Add some ice to a tall glass. Pour in the espresso, then milk, then matcha. If you'd like to layer the drink (rather than having it all it mix together immediately), hold a spoon tipped very slightly downward with the tip touching the side of the glass, pour the milk, then the matcha, into the spoon slowly. Add a straw if you'd like and serve cold.