In a large bowl, combine the flour, baking soda, and all of the spices, including the salt and pepper. Whisk to combine and set aside.
In the bowl of an electric mixer fitted with the paddle attachment, cream the softened butter with the brown sugar on medium speed until fluffy, scraping down the sides if necessary. Add the egg and molasses and mix on low speed until combined. With the motor on low, slowly add the flour mixture. Mix until the dough is consistent in color.
Divide the dough in thirds and wrap each piece in plastic wrap. Refrigerate for 1 hour or up to overnight.
Preheat the oven to 350 degrees F. Allow the dough to sit at room temperature for 10-15 minutes before rolling out. (If the dough chilled overnight, give it more time to warm up before rolling.) On a lightly floured piece of parchment paper or cutting board, roll the dough to 1/4 inch thick. Use cookie cutters to cut out desired shapes. If you would like to hang your cookies from a tree, use a toothpick or skewer to poke holes in the cookies where the string will be threaded. Use a spatula to transfer them to ungreased cookie sheets, and bake for 6-9 minutes, to desired firmness. Allow to cool on the baking sheet for a few minutes before transferring them to a rack to complete cooling.
Decorate the cookies with the royal icing and allow them to dry completely before threading with twine to hang.
Preparation: Royal Icing
Combine the lemon juice and egg whites in the bowl of a stand mixer fitted with the whisk attachment. Whisk on medium-high speed until fluffy. Add 3 1/2 cups powdered sugar and mix until well incorporated and free of lumps. For a thicker icing, add the additional 1/2 cup of powdered sugar. Ice the cookies as desired, using a ttoothpick or piping bag to add details.
Once the frosting has dried, the cookies can be hung using twine, or they can be stored in an airtight container for up to 1 week or frozen for 2 weeks.