Preheat oven to 350º F.
Cream butter and 2 cups of sugar in a large mixing bowl (leave the 1/4 cup of sugar to roll dough in). Add eggs and mint and blend well.
Combine flour, cocoa, baking soda and salt. Blend into creamed mixture.
Using a spoon or cookie scoop, roll dough into balls, then roll in the 1/4 cup of sugar set aside. Then drop mixture onto uncreased cookie sheet.
Bake for 8-9 minutes. They will puff up slightly during baking and flatten upon cooling. Cool on cookie sheet until set, about one minute, then move to wire rack to cool completely.