Preheat oven to 350°F.
Line 8" x 8" square baking pan with parchment paper. (You can use either glass or metal).
In a large bowl, combine mochiko flour, sugar, baking powder, salt. Sift in matcha powder. Whisk all the dry ingredients to combine.
In medium glass bowl, whisk together the egg, oil, and milk.
Pour the wet ingredients over top the dry ingredients.
Use a spatula and mix until everything is combined and there are no lumps.
Pour the batter into the prepared pan.
Tap the pan a few times gently to release any bubbles.
Place in the centre of the oven and bake at 350°F for 35-40 minutes, or until a toothpick inserted comes out clean.
Remove, and let cool on a wire rack.
Slice into 16 small squares. Dust with additional matcha powder.
Best enjoyed freshly made. Keep at room temperature in an airtight container for up to 2 days. Do not refrigerate.