Preheat oven to 350°F. Line 2 baking sheets with parchment paper.
Using an electric mixer, beat butter and sugar in large bowl until well blended. Beat in eggs and peppermint extract. Gradually add flour, cocoa powder, baking soda, baking powder and salt and beat until well blended. Stir in chocolate chips. Form dough into 1-inch balls. Place 2 inches apart on prepared baking sheets. Flatten balls slightly.
Bake cookies until edges begin to firm but center still appears soft, about 9 minutes. Cool on baking sheets 5 minutes. Transfer cookies to racks and cool completely.