Preheat oven to 375 degrees F.
In the bowl of a mini food processor, combine mint and sugar. Process until mint is finely chopped. Set aside.
In a small bowl, whisk together flour, baking soda and salt.
In the bowl of a standup mixer fitted with the paddle attachment, beat butter, mint sugar, brown sugar and vanilla extract until creamy. Add eggs, one at a time, beating well after each addition.
Gradually beat in flour mixture. Stir in chocolate pieces.
Drop by two to three tablespoon-sized balls onto ungreased baking sheets.
Bake for nine to 11 minutes or until golden brown.
Cool on baking sheets for two minutes, and then transfer to wire racks to cool completely.