How to Make It
Preheat oven to 350°F. Beat butter and brown sugar in a stand mixer fitted with a paddle attachment on medium speed until smooth, about 1 minute. Add egg; beat until just combined. Beat in molasses and vanilla until smooth, about 1 minute.
Stir together flour, crystallized ginger, cocoa, baking soda, baking powder, cinnamon, salt, and ground ginger in a bowl. Gradually add flour mixture to butter mixture, beating on low speed until just combined, about 1 minute. Fold in chocolate chunks.
Scoop dough using a 1 1/2-inch cookie scoop. Arrange balls 2 inches apart on 2 baking sheets lined with parchment paper. Working in 2 batches, bake in preheated oven until cookie tops are crackly but cookies are still soft to the touch, 9 to 11 minutes. Let cool on baking sheets 5 minutes.