1. In a medium bowl, whisk flour, baking soda, ginger, cinnamon, cloves and salt.
2. In a large bowl, beat butter and sugar until smooth. Beat in egg, then molasses. Stir flour mixture into butter mixture. Divide dough in half, wrap and chill for 2 hours.
3. Heat oven to 350 degrees . On a well-floured surface, roll half of dough to 1/8-inch thickness. Cut into shapes with assortedsize gingerbread cookie cutters; transfer to ungreased baking sheets. Re-roll scraps and cut. Repeat with rest of dough.
4. Bake at 350 degrees for 13 minutes. Transfer cookies to racks to cool. Decorate with Royal Icing, if using.Royal Icing
5. 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.