Step 1

Line two baking sheets with parchment. In a medium bowl, sift together flour, ground ginger, cinnamon, cloves, nutmeg, and cocoa.

Step 2

In the bowl of an electric mixer fitted with the paddle attachment, beat butter and grated ginger until lightened, about 4 minutes. Add brown sugar; beat until combined. Add molasses; beat until combined.

Step 3

In a small bowl, dissolve baking soda in boiling water. Beat half of flour mixture into butter mixture. Beat in baking-soda mixture, then remaining half of flour mixture. Mix in chocolate; turn out onto a piece of plastic wrap. Pat dough out to about 1 inch thick; seal with wrap. Refrigerate until firm, 2 hours or overnight.

Step 4

Heat oven to 325 degrees. Roll dough into 1 1/2- inch balls; place 2 inches apart on prepared baking sheets. Refrigerate 20 minutes. Roll in granulated sugar. Bake until the surfaces crack slightly, 10 to 12 minutes, rotating halfway through. Let cool on sheets 5 minutes, then transfer cookies to a wire rack and let cool completely. Cookies are best the day they are made but can be stored in an airtight container at room temperature up to 5 days.