01 - Preheat the oven to 350°F. Line two large baking sheets with parchment paper.
02 - In a medium bowl, whisk together the flour, ground ginger, cinnamon, cloves, nutmeg, baking soda, and salt.
03 - In a large bowl, beat the softened butter and dark brown sugar until light and fluffy. Add the molasses and egg, mixing until fully combined.
04 - Gradually incorporate the dry ingredients into the wet mixture, mixing until a stiff dough forms.
05 - Divide the dough into two halves, flatten each into a disk, wrap with plastic wrap, and refrigerate for at least 30 minutes.
06 - On a lightly floured surface, roll out dough to 1/4 inch thickness. Use templates or cookie cutters to cut shapes suitable for a gingerbread house or cookies.
07 - Place cutouts on the prepared baking sheets and bake for 12 to 15 minutes until edges are firm. Let cool completely on wire racks.
08 - Beat egg whites and cream of tartar until frothy. Gradually add powdered sugar while beating until stiff peaks form. Transfer the icing to a piping bag.
09 - Assemble gingerbread pieces using royal icing as adhesive. Decorate with candies and sprinkles as desired. Allow icing to set completely before handling.