1. Preheat your oven to 350°F and line a 12-cup muffin tin with paper liners

2. Cream the butter and sugar together until light and fluffy

3. Beat in the eggs one at a time, then stir in the vanilla extract

4. In a separate bowl, whisk together flour and baking powder

5. Alternately add the flour mixture and milk to the butter mixture, mixing until smooth

6. Divide batter evenly among liners, filling each two thirds full

7. Bake for 18 to 22 minutes or until a toothpick comes out clean

8. Let cupcakes cool in the pan for 5 minutes, then transfer to a rack to cool completely

9. Tint the buttercream with green gel food coloring until you reach the desired shade

10. Fill a piping bag fitted with a star tip and pipe swirls to form tree shapes

11. Decorate each tree with sprinkles and top with a mini marshmallow or candy star