In large mixer bowl, combine brown sugar, 1/3 cup butter, molasses, egg and orange peel. Beat at medium speed, scraping bowl often, until smooth and creamy (1 to 2 minutes). Add all remaining dough ingredients. Reduce speed to low. Continue beating scraping bowl often, until well mixed (1 to 2 minutes). Cover; refrigerate at least 2 hours. Preheat oven to 375°F. On well floured surface roll out dough, ½ at a time (keeping remaining dough refrigerated), to ¼ -inch thickness. Cut with 3 to 4 inch cookie cutters. Place 1 inch apart on greased cookie sheets. Bake 6 to 8 minutes or until no indentation remains when touched. Cool completely. In small mixer bowl combine all frosting ingredients. Beat at low speed, scraping bowl often, until fluffy (1 to 2 minutes). If desired color frosting with food coloring. Decorate cookies. Makes 4 dozen.