Method
Preheat oven to 350°F (175°C).
Cream butter and sugars until light and creamy.
Add egg, vanilla, and peppermint extract.
Whisk the dry ingredients separately.
Gradually mix the dry ingredients into the wet mixture.
Fold in mint M&Ms and chocolate chips.
Scoop dough onto a parchment-lined baking sheet.
Bake for 9–11 minutes.
Cool for 5 minutes on the baking sheet.
Transfer to a cooling rack.