1. In a large bowl, beat shortening, sugar and maple syrup on medium-high until well combined. On low, beat in egg and vinegar until blended.
2. In a medium bowl, whisk flour, baking powder, baking soda, ginger, cinnamon and salt. Add flour mixture to shortening mixture, 1 cup at a time, stirring until incorporated. Stir in maple flavoring. If mixture is very soft, mix in a few extra tablespoons flour. Transfer to a sheet of plastic wrap and flatten. Wrap and refrigerate at least 3 hours or overnight.
3. Heat oven to 375 degrees . Line 2 baking sheets with parchment. Remove 1/4 of the dough from refrigerator; rewrap the rest. On a well-floured surface, roll out dough (it will be soft) to 1/4-inch thickness. Cut out gingerbread men shapes and transfer to prepared baking sheets with a metal spatula, re-rolling scraps. Continue with remaining dough, lining each baking sheet with new parchment. Bake cookies at 375 degrees for 8 to 10 minutes. Cool on sheet pans for 3 minutes, then transfer to wire racks to cool completely.Royal Icing
4. In a bowl, beat confectioners' sugar, powdered egg whites and 3 tbsp water until thick and shiny, about 5 minutes. Transfer to a pastry bag with a writing tip. Outline cookies and pipe on dots of frosting; add M&M's minis as buttons. Let dry.