Italian Polenta Cookies

I found this tasty recipe at www.marthastewart.com

1 3/4 cups all-purpose flour
1 cup Italian polenta or coarse yellow cornmeal
1/2 teaspoon salt
1 cup (2 sticks) unsalted butter, room temperature
2/3 cup sugar
1 tablespoon finely grated lemon zest
1 large egg plus 1 large egg yolk
1 teaspoon pure vanilla extract

Preheat oven to 350 degrees. Whisk together flour, polenta, and salt in a bowl.
Put butter, sugar, and lemon zest in the bowl of an electric mixer fitted with the paddle attachment; beat on medium-high speed until pale and fluffy, about 2 minutes, scraping down the sides of the bowl as needed. Add egg and egg yolk, one at a time, beating after each addition to combine. Mix in vanilla. Gradually add flour mixture, and beat until just combined. Transfer batter to a pastry bag fitted with a 7/16-inch star tip (such as Ateco #825).
Pipe S shapes about 3 inches long and 1 inch wide, spacing 1 1/2 inches apart on baking sheets lined with parchment. Chill in freezer until dough is firm, about 30 minutes. Bake cookies until edges are golden, 15 to 18 minutes, rotating sheets halfway through. Transfer cookies on parchment to wire racks; let cool about 10 minutes. Remove cookies from parchment, and transfer to racks to cool completely. Cookies can be stored in an airtight container at room temperature up to 1 week