Preheat the oven to 350F and line a baking sheet with parchment paper.
In a medium sized bowl add the almond flour, oat flour, baking soda, sea salt and sift in the matcha. Stir until there are no clumps.
Add the melted coconut oil, maple syrup, vanilla to the dry mixture and stir until combined. The dough will feel quite sticky and moist.
Form the dough into a large ball and roll it out between two pieces of parchment paper until it is 1/4 inch thick. Cut out the cookies and using a small offset spatuala carefully transfer the cookies on to the baking tray. If the cookies stick to the cutter or spatula you can put a bit of oil on them. Handle the cookies with care as they are quite delicate.
Form the leftover dough into a ball and repeat the process until you have used up all of the dough.
Bake for 5 minutes. Let them cool for a few minutes on the pan before transfering to a cooling rack.
icing
Once the cookies have completely cooled start on the icing. Place the icing sugar into a small bowl and add the almond milk by teaspoon, stirring to combine. The icing should be quite stiff, but still able to pipe.
If you don't have a piping bag, place the icing into a ziplock bag and push it to the bottom corner of the bag. Cut a very small piece off the tip. Ice the cookies in a zig zag motion (or however you like). The icing will set in about 10 minutes.
These cookies are best eaten fresh the same day, but can be stored sealed in the fridge for up to 3 days. (Matcha powder oxidizes quite quickly so the cookies will become darker in colour the longer they're stored.) Enjoy!