Place granulated sugar and butter in a large bowl; beat with a mixer at medium speed until smooth and well blended.
Add molasses and egg; beat until well blended.
Stir flour mixture into sugar mixture until well blended.
Divide dough in half; shape each dough portion into a flat disk. Wrap dough portions separately in plastic wrap; chill 1 hour or until firm.
Preheat oven to 350°
Remove 1 dough portion from refrigerator; remove plastic wrap. Roll dough to a 1/8-inch thickness on a floured surface.
Cut with a 3-inch boy or girl cookie cutter. Place cookies 1/2 inch apart on parchment paper-lined baking sheets.
Repeat procedure with remaining dough portion. Bake at 350° for 11 minutes or until edges of cookies are lightly browned. Remove from pans; cool completely on wire racks.
Combine powdered sugar and milk, stirring until smooth.
Spoon mixture into a heavy-duty zip-top plastic bag.
Snip a tiny hole in 1 corner of bag. Pipe onto cookies.
Decorate as desired with sugar sprinkles