Preheat oven to 350 degrees and prepare a baking sheet with a silicone liner or parchment paper. Set aside.
Using a hand-held mixer, blend together the brown sugar and butter until light and fluffy.
Add the egg and salt. Mix into the butter mixture.
Add the flour, baking soda, and matcha powder. Mix until just incorporated. Do not over mix.
Use a small cookie scoop, about 1 tablespoon in size, to scoop the cookie batter into even portions. Roll into balls and roll into the confectioner's sugar until well coated.
Place the dough on the baking sheet, about 1 inch apart. Bake for 15 minutes. Remove from oven and immediately transfer to a wire cooling rack to completely cool.