Preheat oven to 400F. In large mixer bowl, Combine sugar, butter, egg, salt, nutmeg, and vanilla. Beat at medium speed, scraping bowl often, until mixture is light and fluffy, 2 to 3 minutes.
Add flour, and beat at low speed, scraping often, until well mixed, 2 to 3 minutes. If dough is too soft, cover and refrigerate until firm enough to form cookies, 30 to 45 minutes.
Place dough in cookie press and press out onto ungreased cookie sheets. Bake for 6 to 8 minutes or until edges are lightly browned.
In small bowl, stir all ingredients until smooth. Drizzle or pipe over warm cookies.