Preheat oven to 350 degrees. Line baking sheets with silicon baking mats or parchment paper.
In a large bowl or stand up mixer, cream together the butter and sugar. Beat in the cocoa powder, milk powder, vanilla, and egg. Whisk together the flour, baking soda, and salt and add to batter, mixing well to combine. Fold in the chocolate chunks and chips.
Use a cookie scoop to scoop out evenly shaped balls of dough on to baking sheet, leaving about 3 inches between each cookie. Bake for 12-14 minutes. Cool on wire rack.
Make-ahead and freeze! Just place cooled cookies in a zip top bag and freeze for up to two months.
Recipe courtesy of This Delicious House. Sign up for more recipes today at https://thisdelicioushouse.com