01 - Preheat oven to 350°F. Line two 12-cup muffin pans with cupcake liners.
02 - Whisk together flour, baking powder, baking soda, and salt in a bowl.
03 - In a large bowl, beat butter and sugar until light and fluffy. Add eggs one at a time, then vanilla.
04 - Add dry ingredients in three parts, alternating with milk. Begin and end with flour mixture. Mix until just combined.
05 - Divide batter evenly among liners, filling about 2/3 full. Bake for 18–20 minutes or until a toothpick comes out clean. Cool completely on a wire rack.
06 - Beat butter until creamy. Gradually add powdered sugar, then vanilla and milk as needed for desired consistency. Tint with green gel food coloring.
07 - Using a large star tip, pipe tall swirls of green buttercream onto each cooled cupcake.
08 - Arrange cupcakes on a large board or platter in a tree shape: 7 at the base, then 6, 5, 4, and finish with 2 and 1 at the top.
09 - Decorate with sprinkles as ornaments. Place gold star at the peak. Add candy canes, pearls, or coconut for extra decoration.