Melt half of the Andes baking chips in 30-second intervals, stirring between each interval, until smooth. Set aside to cool until just warm.
In a separate bowl, whisk together the flour, baking soda, and salt. Set aside.
Mix the softened butter, brown sugar, and granulated sugar until smooth and lightly creamy. Add the egg and vanilla and mix until incorporated.
Stir the melted mint chocolate mixture into the butter mixture until evenly combined.
Add the flour mixture and mix just until no dry flour remains. Do not overmix.
Fold in the remaining Andes baking chips until evenly distributed.
Portion the dough into 2-ounce balls and place on a parchment-lined tray. Refrigerate for 30 to 60 minutes before baking.
Heat the oven to 375°F. Bake for 11 to 13 minutes, until the edges are set and the centers remain soft. To bake from frozen, add 1 to 2 minutes.
Cool. Cool the cookies on the baking sheet for 5 minutes before transferring to a wire rack.