Cream butter and sugars in a large mixing bowl till creamy and light. Add eggs and vanilla and beat until well combined.
Whisk together flour, salt, and soda. Stir into wet ingredients. Set aside about 1/2 cup of the Andes baking chips. Add the remaining baking chips and the chocolate chips. Stir till just combined.
Cover dough and let chill for at least an hour, overnight is better. The mint flavor really improves as it chills!
Roll dough into 1 1/2″ sized balls and place on lightly greased or silpat lined cookie sheets. Bake at 350° for about 12 minutes. Let sit on pans for 3-5 minutes, then remove to cooling racks.
Melt the remaining baking chips and drizzle over the cookies.