1. In a large bowl, whisk together flour, baking soda, spices and salt. In another large bowl, using an electric mixer on medium-high speed, cream together butter and shortening. Add sugar and beat until light and fluffy, about 3 minutes. Beat in molasses and egg. Scrape down 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 up to overnight.
2. Preheat oven to 350ºF; 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 re-roll to form more cookies. Repeat with remaining dough disk.
3. Bake cookies for 10 to 12 minutes, switching sheets top to bottom and front to back halfway through. Cool cookies on baking sheets on wire racks for 5 minutes, then transfer to racks to cool completely. Repeat with remaining cookies.