Preheat the oven to 340°F/170°C. Line muffin-cupcake tray with paper liners. Set aside. Sift whole wheat flour, oat flour, baking powder, baking soda, soda, sugar, salt, and matcha powder into a medium bowl.
In a separate small bowl, whisk together yogurt, oil, egg, and vanilla extract until combined.
Add the flour mixture to the yogurt mixture and gently fold until the batter is smooth. Avoid over mixing.
Divide the batter amongst 12 muffin liners.
Bake for 15-18 minutes until an inserted toothpick comes out clean.
Allow the muffins to cool in the pan for five minutes before removing. Transfer to a wire rack to cool completely.
Store muffins in an airtight container in a cool dry place for up to three days. Glaze with lemon icing!