Prepare the dry ingredients: Begin by sifting together the all-purpose flour, unsweetened cocoa powder, baking powder, salt, ground cinnamon, allspice, black pepper, and cayenne pepper in a medium bowl. Ensure the spices are evenly distributed throughout the dry ingredients.

Cream the butter and sugar: In a large mixing bowl, cream together the softened unsalted butter and granulated sugar until the mixture becomes light and fluffy. This process typically takes about 3-4 minutes. Then, add the egg and vanilla extract, and continue mixing until smooth and well-incorporated.

Combine wet and dry ingredients: Gradually add the dry ingredients to the butter mixture, mixing just until everything is combined. Avoid overmixing as this could result in a denser texture for the cookies.

Chill the dough: Once the dough is well-mixed, cover it and place it in the refrigerator for about 30 minutes. Chilling the dough allows it to firm up, making it easier to shape later.

Form the dough logs: After chilling, divide the dough into two equal portions. Roll each portion into a log about 3 inches in diameter. Wrap each log tightly in plastic wrap and place them in the freezer for 1-2 hours, or until completely firm.

Prepare to bake: Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper. Remove the dough from the freezer and, using a sharp knife, slice the dough into rounds approximately ½ inch thick. Arrange the slices on the prepared baking sheet, leaving space between each one for spreading.

Bake the cookies: Bake the cookies for 9-11 minutes, ensuring that they are firm around the edges but still slightly soft in the center. They will continue to firm up as they cool. Allow them to rest on the baking sheet for a few minutes before transferring to a wire rack to cool completely.

Store: Once cooled, store the cookies in an airtight container at room temperature for up to one week. Alternatively, they can be refrigerated or frozen for longer storage.