Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth and fluffy.
Add in the egg, vanilla extract, and peppermint extract, mixing until well combined. If you'd like a brighter green hue, add a few drops of green food coloring and mix until evenly colored.
In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add this dry mixture to the wet ingredients, stirring until just combined. Avoid overmixing.
Fold in the semi-sweet chocolate chips and mint chocolate chips until evenly distributed throughout the dough.
Using a tablespoon or cookie scoop, drop rounded balls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden but the centers are still soft.
Remove from the oven and allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.
Notes
Stack the cookies on a decorative plate and sprinkle a few extra mint chocolate chips on top for added visual flair. Serve with a glass of cold milk for a delightful pairing!