Cream butter and brown sugar in a stand mixer. Add molasses, salt, cocoa powder, and egg. Beat until thoroughly mixed and slowly add flour. Mix until a dough ball forms. Remove the dough from the mixing bowl, and roll out 1/8 inch thickness on floured cutting table.
Using pentagon shape template, cut out as many shapes as you need (12 pentagons per cookie) and bake for 6-8 minutes.
Once out of the oven, cover with parchment. Using a slightly smaller baking sheet, press down on cookies to ensure they are smooth.
In a stand mixer, beat egg whites till frothy. Add sugar until desired consistency is reached.
Once cookies have cooled, assemble halves using royal icing. (This part is hard so be patient. I printed out the pattern, cut it out, and taped the edges together and trimmed about a 8th inch off the bottom points. Then, I flipped it upside down and assembled cookies over it. Once set, I removed it. There may be an easier way to do it, but this method worked for me.).
After your halves have set and dried, glue them together using royal icing. Once that sets, use a dremel tool to perfect the edges, carve out one of the faces for the teeth, and created grooves along all the edges.
Decorate it with royal icing and use some gold powder paint to highlight the desired areas.