Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans.

In a medium bowl, whisk together the flour, baking powder, and salt.

In a large mixing bowl, cream the softened butter and granulated sugar together until light and fluffy.

Add the eggs one at a time, mixing well after each addition, then blend in the vanilla extract.

In a separate bowl, mix the matcha powder with the buttermilk.

Gradually add this mixture to the butter and egg mixture, alternating with the flour mixture, beginning and ending with the flour.

Stir in the crushed pistachios.

Pour the batter evenly into the prepared cake pans and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Once baked, let the cakes cool in the pans for about 10 minutes before transferring them to wire racks to cool completely.

In a large bowl, beat the softened butter until creamy. Gradually add the powdered sugar and milk until smooth. Mix in matcha powder and salt until well combined.

Once your cakes are fully cooled, place one layer on a serving plate. Spread frosting on top, then add the second layer, placing it face down.

Frost the sides and top, and sprinkle extra crushed pistachios on top.