Preheat the oven to 375°F and line baking sheets with parchment paper.

Using a hand mixer or a stand mixer fitted with a paddle attachment, cream the butter, brown sugar, molasses, cocoa powder, and egg yolk on medium speed until well combined. Scrape down the sides of the bowl so everything mixes evenly.

In a separate bowl, whisk together the flour, ginger, cinnamon, cloves, black pepper, and salt.

With the mixer on low speed, slowly add the dry ingredients to the wet ingredients just until a soft cookie dough forms.

Turn the dough out onto a lightly floured surface and knead gently until smooth. Divide the dough in half, shape each portion into a disc, and wrap tightly in plastic wrap. Chill for 20 minutes.

Lightly flour your work surface and roll out one disc at a time to ¼-inch thickness using a rolling pin. Lightly dust the top of the dough with granulated sugar to prevent cookie cutters or stamps from sticking.

Cut out shapes using cookie cutters or stamps and transfer to parchment-lined baking sheets. Chill the cut-out cookies for 10 minutes before baking.

Bake one cookie sheet at a time. Bake for 8 minutes for softer cookies or 9–10 minutes for firmer cookies with a crisp edge. Let the cookies rest on the baking sheet for 10 minutes, then transfer to a wire rack to cool completely.

In a medium bowl, whisk together the powdered sugar, vanilla extract, and milk, adding the milk a little at a time until the icing is thick but brushable.

Use a pastry brush to lightly coat the tops of the cooled cookies. Allow the icing to dry completely before stacking or storing.