1. Whisk together flour and salt in a small bowl.
2. Beat together butter and sugar in a large bowl with an electric mixer at medium-high until pale and fluffy, about 3 minutes in a stand mixer or 6 minutes with a handheld. Beat in egg and vanilla. Reduce speed to low and add flour mixture, mixing until just combined.
3. Form dough into 2 balls and flatten each into a 6-inch disk. Chill disks, wrapped in plastic wrap, until firm, at least 1 hour.
4. Put oven rack in middle position and preheat oven to 350 degrees F.
5. Roll out 1 disk of dough (keep remaining dough chilled) into an 8 1/2-inch round (1/4 inch thick) on a well-floured surface with a well-floured rolling pin. (If dough becomes too soft to roll out, rewrap in plastic and chill until firm.) Cut out as many cookies as possible from dough with cutters and transfer to 2 ungreased large baking sheets, arranging cookies about 1 inch apart.
6. Bake cookies, 1 sheet at a time, until edges are golden, 10 to 12 minutes, then transfer to racks to cool completely.
7. Meanwhile, gather scraps and chill until dough is firm enough to reroll, 10 to 15 minutes. Make more cookies with remaining dough and scraps (reroll scraps only once) and bake on cooled baking sheets.
8. If using icing and coloring it, transfer 1/4 cup icing to a small bowl for each color and tint with food coloring. Spoon each color icing into a sealable bag, pressing out excess air, and snip a 1/8-inch opening in 1 bottom corner of bag. Twisting bag firmly just above icing, decoratively pipe icing onto cookies. Let icing dry completely (about 1 hour) before storing cookies.

Yield: 24 servings