First, let's make the brown sugar syrup. Put 2 tablespoons of brown sugar and 2 tablespoons of water in a small saucepan. Heat it over medium heat and stir until the sugar completely dissolves - this usually takes about 2 minutes. Take it off the heat and let it cool down while you prepare the rest.
While the syrup cools, let's prepare your matcha. Boil some water and let it cool for about 2 minutes (we want hot but not boiling water, around 175°F if you have a thermometer). Put 1 teaspoon of matcha powder through a small strainer into a bowl - this gets rid of any lumps. Add 2 tablespoons of your hot water to the matcha. Using your matcha whisk or frother, mix it in a 'W' or 'M' motion until it's smooth and a bit frothy, with no lumps. This takes about 1 minute.
Now for the fun part - putting it all together. Take your tall glass and pour in the cooled brown sugar syrup. Add enough ice cubes to fill about half the glass. Slowly pour in ¾ cup of cold milk. Finally, gently pour your matcha mixture over the top.
You can either leave it layered and take a pretty picture (it'll have brown sugar at the bottom, white milk in the middle, and green matcha on top), or stir it all together with a long spoon to mix the flavors.
That's it! Take a sip and enjoy your homemade iced brown sugar matcha latte. Remember, if it's not sweet enough, you can always add more syrup, or if it's too strong, add a splash more milk. Make it exactly how you like it.