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 - 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, beginning and ending with flour. Mix until just combined.
05 - Divide batter evenly among liners, filling ⅔ full. Bake 18–20 minutes until toothpick comes out clean. Cool completely on wire rack.
06 - Beat butter until creamy. Gradually add powdered sugar, vanilla, and milk for desired consistency. Tint with green gel food coloring.
07 - Pipe buttercream in tall swirls on cooled cupcakes using a large star tip.
08 - Arrange cupcakes in tree shape on large board: 7 at base, then 6, 5, 4, finishing with 2 and 1 at top.
09 - Add sprinkles as ornaments. Place gold star at peak. Add candy canes, pearls, or coconut for extra decoration.