Preheat oven to 350°F (175°C) and line a muffin tin with green cupcake liners.
In a large bowl, mix together cake mix, milk, melted butter, and eggs.
Add peppermint extract and a few drops of green food coloring. Mix until just combined.
Divide batter evenly into cupcake liners, filling each about ⅔ full.
Bake for 18-22 minutes, or until a toothpick inserted in the center comes out clean.
Let the cupcakes cool completely before frosting.