Preheat oven to 350 degrees.
Line a baking sheet with parchment paper.
In a medium bowl stir together the flour, baking powder and salt.
In a microwave safe bowl melt one cup of the chocolate pieces. Stir every 30 seconds.
In a large mixing bowl beat butter with an electric mixer for thirty seconds on medium speed.
Add sugar, beat until fluffy.
Scrape sides of bowl.
Add eggs one at a time, mix until combined.
Add vanilla and mint extract.
Beat until combined.
Add melted chocolate and mix well.
Gradually beat in flour mixture and ½ cup chocolate pieces until combined.
Cover with plastic wrap and refrigerate for 30 minutes or until dough is easy to handle.
Scoop dough out and roll into 1-inch balls. Roll balls of dough into powdered sugar.
Place on prepared baking sheet 2 inches apart.
Bake for 10 minutes or until tops are crackled.
Cool on cookie sheet for 2 minutes and then transfer to a cooling rack to cool completely.
Store in an airtight container.