Chop chocolate into 1/4-inch chunks; set aside. In a small bowl, dissolve baking soda in 1 1/2 teaspoons boiling water; set aside.

In the bowl of an electric mixer, fitted with the paddle attachment, beat butter with brown sugar until combined. Add fresh ginger and mix until combined. In a medium bowl, sift together flour, cocoa, ground ginger, cinnamon, cloves, and nutmeg. Slowly add to butter mixture, mixing until well combined.

Add baking soda mixture and molasses; mix to combine. Stir in chocolate; Transfer to refrigerator. Refrigerate until firm, at least 2 hours.

Preheat oven to 325 degrees. Line two baking sheets with parchment paper.

Using a 2-inch ice cream scoop, scoop dough onto baking sheet, 2 1/2 inches apart. Refrigerate 20 minutes. Roll dough balls in granulated sugar and return to baking sheets. Transfer to oven and bake until surfaces crack slightly, about 18 minutes. Let cool 5 minutes; transfer to a wire rack to cool completely.