Toast minced walnuts in a heated skillet over medium heat for 2-3 minutes, then let cool.
Microwave butter and unsweetened chocolate for about 1 minute and let cool.
In a large mixing bowl, combine melted chocolate mixture, flour, cocoa powder, sugar, eggs, baking powder, salt, and walnuts. Beat at medium speed until well combined.
Heat oven to 300 F.
Using a 1″ cookie scoop, make cookie balls and roll in granulated sugar. Make sure to coat them completely.
Space 2″ apart on an ungreased cookie sheet, and bake for 15 minutes.
Cool on wire rack.