Preheat oven to 425 F. Lightly grease a donut pan with cooking spray and set aside.
In a large bowl, combine the gluten free flour, cane sugar, baking powder, matcha powder, and salt.
In a separate bowl, whisk together the non-dairy buttermilk, egg, coconut oil, and vanilla extract.
Pour the wet ingredients into the dry ingredients, and stir the mixture together until fully incorporated.
Spoon the batter into the donut pan, filling them about 3/4 of the way.
Bake for about 8-10 minutes, until a toothpick inserted in the center comes out clean.
Cool donuts completely on a wire rack before dipping them in icing.