Preheat the oven to 350°F (180°C) and line a cupcake tray with 12 cupcake liners. Set aside.
Sift the all purpose flour into a mixing bowl and add the white granulated sugar, baking soda, salt and matcha powder. Mix together.
Prepare your vegan buttermilk by adding 1 tablespoon distilled white vinegar to a measuring jug and then adding soy milk up to the 1 cup (240ml) line. Let it sit for a minute to thicken and curdle.
Add the vegan buttermilk, canola oil and vanilla extract and mix into a batter. Don't over-mix.
Divide the batter evenly between the 12 cupcake liners in your cupcake tray.
Bake for 20 minutes or until a toothpick inserted into the center of one of the cupcakes comes out clean.
Let them cool for a few minutes in the cupcake tray and then transfer them to a wire cooling rack to cool completely before frosting.
Add vegan butter, powdered sugar, matcha powder and 2 tablespoons soy milk to the bowl of your stand mixer. Starting at slow speed, gradually increase speed until the frosting is thick and smooth. If it's too thick, add the extra tablespoon of soy milk.
When the cupcakes have cooled completely, pipe on the frosting.