Mix the flour, baking soda, salt, ginger, cinnamon, cloves, and allspice into a bowl. In another bowl mix the butter, shortening, brown sugar, molasses, and beat in 1 egg with a mixer. Beat in the flour mixture one half at a time. Divide the dough in half, wrap in plastic and pat to 1/2 inch thick. Chill for 2 hours.
Preheat the oven to 350º. On a floured surface, roll out each piece of dough to 1/4 inch thick, dusting with flour, if needed. Cut into 3 to 5 inch gingerbread and arrange 1 inch apart on parchment lined baking sheets. Brush off excess flour and chill 15 minutes. Bake until the cookies are golden around the edges, 10 to 12 minutes.
Transfer to a rack and cool, then decorate with Royal Icing.
1 pound confectioners sugar
1/2 tsp cream of tartar
3 egg whites
Add water if necessary to get desired consistency.
Use food coloring for festive colors. Paint on cookies and fill a resealable plastic bag and snip the end for drawing lines and accents.