Preheat oven to 350°F and line a cupcake pan with liners.
Place one whole Oreo cookie at the bottom of each cupcake liner.
In a large mixing bowl, combine cake mix, sour cream, oil, eggs, milk, and vanilla. Mix until smooth.
Fold in mini chocolate chips.
Fill each liner 3/4 full with batter over the Oreo.
Bake for 18–22 minutes or until a toothpick comes out clean.
Cool cupcakes completely before frosting.
Pipe mint buttercream on top and sprinkle with chopped Andes mints.