In a large mixing bowl, combine the softened butter and granulated sugar until light and fluffy. Add the molasses and egg yolk (reserve the egg white for the royal icing) and combine. Add the baking soda, cloves, cinnamon, ginger, and salt, and combine. Add the flour and combine.
Shape the dough into a round ball, then flatten into a round disc or rectangle. Place the dough on a clean work surface dusted with flour. Dust the dough and the rolling pin with flour and roll out the dough such that it is slightly less than ½ inch thick.
Cut out the cookies into gingerbread shapes and place each cut out cookie onto a baking sheet with a little bit of room between the cookies.
Bake in the fully preheated oven for 9 minutes. Allow the cookies to cool slightly, then move them to a cookie drying rack to cool fully.
Decorating the Cookies
Once the cookies have fully cooled, decorate with royal icing. To make the icing, add the eggwhite to a medium mixing bowl and beat until stiff peaks form. Little by little, beat in 2 cups of powdered sugar. Add additional powdered sugar as needed to get an icing that is thick enough for piping, but not runny. If the icing becomes too thick and dry, add a teaspoon of water to thin it out.
Use a piping bag with a simple round tip if you have one. Otherwise, use a thick quart-sized freezer bag without a pleated bottom. Place the bag in a juice glass, turning the top inside out over the top of the juice glass. Add the royal icing. Use scissors to cut off a very small amount of the tip of the bag, then use the bag to pipe the royal icing.Allow the icing to fully harden before storing or stacking the cookies. This may take several hours.The cookies will last for a week or more when stored in an airtight container at room temperature.
Notes
Spices:
Use a high-quality Ceylon cinnamon if possible.
The ginger flavor in these cookies is strong, but not overpowering. Feel free to tone it down slightly if someone prefers a less ginger flavor in their gingerbread cookies.
Measuring Flour: To be precise, use a kitchen scale to weigh the flour in grams. Or make a test cookie first, and adjust the amount of flour as needed, or add a teaspoon of water if the dough is too dry.
Royal Icing: Some royal icing recipes use cream of tartar. You can add a ¼ teaspoon if you have it, but I do not find it necessary.
Baking Time: The baking time might vary by a minute on either side, depending on how big or thick your cookies are.
Cracking: The cookies may form slight cracks while baking in the oven. This is due to the baking soda in the recipe and the thickness of the cookies, which causes the cookies to rise, but it also prevents them from being overly dense or thin and hard. As they cool, the appearance of cracks will lessen significantly and become less noticeable.
Make Ahead: These cookies are great for making ahead. Make the dough up to a week in advance (store in the fridge, or longer in the freezer), or make the cookies themselves several days in advance. This also makes them great cookies for mailing to friends and family around the holidays.