In a large pan over low heat, cook butter, sugar and water until butter is melted. Add chocolate chips and stir until partially melted. Remove from heat and continue to stir until chocolate is completely melted. Pour chocolate mixture into a large bowl and let stand 10 minutes to cool slightly.
In a medium bowl, combine flour, baking soda, and salt; set aside.
At medium speed, beat eggs into chocolate mixture, one at a time. Reduce speed to low and add the flour mixture in two additions, mixing until just combined after each addition. Chill dough for at least 1 hour in the refrigerator.
Preheat oven to 350 degrees F. Line a baking sheet with a Sil-Pat or parchment paper.
Portion dough by the tablespoonful onto prepared the baking sheet, about 2 inches apart. Bake for 10 to 12 minutes, until cookies are cooked through.
Remove cookies from the oven, and place 1/2 mint on top of each cookie. Let the mint sit for 1 to 2 minutes until melted, then spread the mint on top of the cookie. The mint will still look normal, but it will be soft and spreadable. Cool completely before eating.
If you can't find Andes mints, candy cane Hershey kisses or chocolate/mint chips would work just fine too.If you want more "frosting" on each cookie you can use a whole Andes mint instead of half.