Place sugar, molasses, cinnamon, cloves, ginger, allspice, cayenne and salt in a small saucepan. Set saucepan over medium heat and bring mixture to a boil, stirring often as it heats. When mixture starts to boil, remove from heat and stir in baking soda. Mixture will fizz up and become very airy and light.
Add the chunks of shortening one piece at a time, stirring after each. It's okay if it doesn't melt completely at this point, but it should at least start to melt. Allow mixture to cool for about 3 minutes, then briskly stir in the egg yolk or 2 tablespoons beaten egg' Using yolk only makes a slightly thinner, harder cookie while 2 T. egg makes a crunchy but tad bit lighter texture. The yolk might be more convenient because you can save the white for the icing.
Carefully measure or weigh your flour and put it in a large mixing bowl. After you've added the egg to the molasses mixture, scrape all of the molasses mixture in with the flour and stir to make a dough. It might look kind of dry, but should have a nice feel to it. Empty it onto a clean surface (pastry mat) and knead very gently to incorporate all flour.
Shape the dough into a rectangle, then gently roll and smooth until it is a little over 8x10 inches with the short sides closest to you. Using the straight edge of a ruler and a knife, trim score edges so they are straight. Do not separate the trimming yet, just score them. Next, cut a vertical line down the center, then make 5 horizontal cross-wise cuts so that you have 10 rectangles.
Carefully transfer each rectangle (plank) to the parchment lined baking sheet. Put the trimmings around the edges of the baking pan so that you'll have some snackin' scraps. Bake at 325 F for about 14 minutes. Let cool on baking sheet for about 5 minutes, then transfer to a wire rack to cool completely.
In a mixing bowl, combine egg white and vanilla and beat with an electric mixer for about 30 seconds. Add confectioners' sugar gradually and stir until sugar is moistened. With the electric mixer, beat until smooth and shiny, adding a tiny bit red food coloring and a tiny bit of water if needed or more sugar if mixture is too thin. Spoon icing over cookies and let them sit out for about an hour or two until the icing has hardened.