Opal's Walnut Shortbread Cookies

In a large mixing bowl, beat butter on medium speed to high speed for 30 seconds. Add sugar and salt. Beat until combined, scraping sides of bowl occasionally. Beat in egg and vanilla until combined. Beat in as much of the flour as you can with the mixer. Stir in any remaining flour. Stir in walnuts.

Drop dough by rounded teaspoons 2 inches apart onto ungreased cookie sheets. Using your fingers, flatten dough.

Bake in a 325°F oven for 8 minutes. Rotate cookie sheet front to back. Bake for 5 minutes more or until edges are firm and tops are lightly browned. Transfer cookies to a wire rack; cool completely. If you like, drizzle cookies with Powdered Sugar Icing.