1. Whisk together flour, baking soda, spices and salt. In a large bowl, using an electric mixer on medium-high speed, cream butter and shortening. Add sugar and beat until fluffy, about 3 minutes. Beat in molasses and egg. Scrape sides of bowl, then stir in flour mixture to form a stiff dough. Divide dough in half. Form into 2 disks, wrap in plastic wrap and refrigerate for 4 hours or overnight.
2. Preheat oven to 350°F; line 2 large baking sheets with parchment. Roll out 1 disk of dough on a lightly floured surface to 1/8-inch thickness. Cut out cookies with a 3-inch cutter and place 1 inch apart on baking sheet. Gather scraps and reroll to form more cookies. Repeat with remaining dough.
3. Bake cookies for 10 to 12 minutes, switching sheets top to bottom and front to back halfway through. Let cool for 5 minutes on baking sheets on wire racks. Transfer cookies to racks to cool. Repeat with remaining cookies.