This year, butter up your sweethearts with a batch of sugar-cookie hugs and kisses. Make bite-size X's and O's for a bunch of friends or a pair or giant letters for a special sweetie.
In a large bowl, cream the butter and sugar until fluffy. Add the egg and beat well, then mix in the vanilla extract. In a separate bowl, combine the flour, baking soda and cream of tartar. Add the flour mixture to the butter mixture, one third at a time, until thoroughly combined.
Divide the dough into 2 equal portions and flatten each into a disk. Cover each disk in plastic wrap and refrigerate for 2 to 3 hours, or until the dough is firm enough to work with. If it becomes too firm, soften at room temperature for about 5 minutes.
Preheat the oven to 350 degrees. On a floured surface, roll out the dough to a 1/4-inch thickness. Then, use a butter knife to cut out the cookies into X's and O's. Remind your child that giant letters need to be wider than smaller ones to keep them from breaking easily.
Using a metal spatula, carefully transfer the cookies to a baking sheet, leaving about 2 inches between them. Bake for 8 to 10 minutes (longer for really big cookies) or until lightly browned around the edges.
Remove the cookie sheets from the oven, place on wire racks and cool for 2 to 3 minutes. Using a metal spatula, transfer the cookies to the rack and cool completely. Makes about 3 dozen cookies, depending on their size.
While the cookies are cooling, make the buttercream icing: Beat together the sugar, butter and vanilla extract. Add the milk a few drops at a time until the mixture is spreadable. Makes 1 1/2 cups.
Frost the cookies with the icing and sprinkle on tinted red or pink sugar, if desired.