Beat butter and sugar. Beat in egg and molasses. Combine flour, cocoa, baking soda, ginger, pepper and cinnamon in another bowl. Stir into butter mixture. Divide dough into 2 halves. Wrap; chill 2 hours.
Heat oven to 350°F. Roll half of dough on a floured surface to 1/8 inch thick. Cut shapes with a 3-inch cutter; transfer to ungreased baking sheets. Reroll scraps; cut. Repeat with remaining dough.
Bake at 350°F for 11 minutes. Transfer cookies to racks to cool. Decorate with Royal Icing; do not thin with extra water.