Sift together flour, xanthan gum baking soda, and baking powder into a large bowl. Set aside.
15 ounces gluten free flour, ½ teaspoon xanthan gum, ½ teaspoon baking soda, ¼ teaspoon baking powder, ½ teaspoons kosher salt
Put butter and brown sugar in the bowl of an electric mixer fitted with the paddle attachment; mix on medium speed until fluffy. About 3 minutes. Mix in spices and salt, then add the egg, molasses, and vanilla. Reduce speed to low.
½ cup unsalted butter, ½ cup packed dark-brown sugar, 2 teaspoons ground ginger, 2 teaspoons ground cinnamon, ¾ teaspoons ground cloves, ¼ teaspoon allspice, ¼ teaspoon finely ground pepper, 1 large egg, ½ cup blackstrap molasses
Add flour mixture; mix until just combined. You may use more or less of the flour by a tablespoon or two, depending on the humidity of your environment.
Divide dough and form into 2 flat discs. Wrap each in plastic wrap and refrigerate until cold, about 1 hour.
Preheat oven to 350 F degrees. Roll out dough on a lightly floured work surface to a ¼-inch thick. If the dough is sticking you can roll out between two pieces of parchment paper. Cut into desired shapes. Space 2 inches apart on baking sheets lined with parchment paper, and refrigerate until firm, about 15 minutes.
Bake cookies until crisp but not dark, 12 to 14 minutes. Let cool on sheet for 3 to 5 minutes before moving on to wire racks. Wait until fully cooled to decorate.
Royal Icing, Sanding sugar for sprinkling
Blackstrap molasses provides a richer flavor and deeper color. Regular unsulphured molasses can be substituted for a lighter color and flavor.
Cookies can be made one day and decorated another.
It is recommended you let the cookie dry overnight when making gingerbread houses.
Cookies can be kept in an airtight container at room temperature for up to a week.