Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside. In a large bowl, beat the butter and sugar until light and fluffy, about 2 minutes.
Add the eggs one at a time, mixing well after each, then stir in the vanilla extract.
Gently mix in the dry ingredients and the buttermilk/milk mixture, alternating between them. Stop mixing once the batter is smooth.
Stir in the green food coloring and matcha powder (if using) until the cupcakes have an even green color.
Divide the batter evenly into the cupcake liners, filling each about ¾ full.
Bake for 18–20 minutes, or until a toothpick inserted in the center comes out clean. Let the cupcakes cool completely.
For the frosting, beat the butter until creamy. Gradually add the powdered sugar, then mix in vanilla, salt, and cream until light and fluffy.
Pipe or spread the frosting on the cooled cupcakes. Decorate with chocolate shavings, sprinkles, or any festive toppings you like.
Serve and enjoy!