Cream the butter and sugar. Place the softened unsalted butter and dark brown sugar in a mixing bowl. Beat them together for several minutes, continuing until the mixture becomes pale, light, and fluffy.
Add the remaining wet ingredients. Pour in the molasses and 1 teaspoon vanilla extract. Beat at high speed for approximately 1 minute. Add the large egg and continue mixing until it is completely incorporated.
Prepare the dry mixture. In a separate bowl, thoroughly combine the all-purpose flour, baking soda, ground ginger, cinnamon, allspice, cloves, and a pinch of salt.
Form the gingerbread dough. Gradually introduce the dry ingredients to the wet mixture while mixing at low speed. Continue only until a smooth, evenly combined dough forms.
Chill the dough. Separate the dough into two equal portions and wrap each piece securely in plastic wrap. Refrigerate for 2–3 hours. For the best results, the dough may instead be refrigerated overnight.
Roll and cut the cookies. Once thoroughly chilled, transfer the dough to a lightly floured work surface and roll it to the preferred thickness. Cut out gingerbread man shapes with a suitable cookie cutter and arrange them on a parchment-lined baking sheet.
Chill the shaped cookies. Place the tray of cut cookies in the refrigerator for an additional 30 minutes so the shapes become firm before baking.
Bake. Preheat the oven to 350°F (175°C), the typical temperature indicated in the original directions because a specific baking temperature was not otherwise supplied. Bake the cookies until they appear golden and feel firm when gently touched. The precise baking duration will vary according to the thickness of the cookies and the oven being used.
Cool completely. Remove the baked gingerbread cookies from the oven and allow them to cool at room temperature before decorating.
Prepare the royal icing. Combine the egg white, sifted powdered sugar, and ¼ teaspoon vanilla extract. Mix until the icing develops a thick yet flowing consistency. If necessary, incorporate a few drops of water to achieve the required texture.
Color the icing. Divide the royal icing into three portions. Tint one portion with red food coloring and another with green food coloring, leaving the third portion uncolored.
Decorate the cookies. Once the gingerbread men are completely cool, decorate them with the red, green, and plain royal icing as desired.