Preheat your oven to 350°F (175°C) and line a cupcake pan with paper liners.

In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and matcha powder until well combined.

In another bowl, beat the softened butter until creamy. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk. Mix until just combined, being careful not to overmix.

Divide the batter evenly among the cupcake liners, filling each about two-thirds full. Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean. Let the cupcakes cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.

For the frosting, beat the softened butter until creamy. Gradually add the powdered sugar, mixing on low speed until combined. Add the heavy cream, matcha powder, and vanilla extract, then beat on high until fluffy and smooth.

Once the cupcakes are completely cool, frost them with the matcha frosting using a piping bag or a spatula.