French-Swiss Butter Cookies

Makes about 5 dozen cookies.
Taste Tip: This dough must be prepared in advance.
1 cup (2 sticks) butter
1 cup sugar
1 egg, divided
2½ teaspoons ground cinnamon
2 cups flour, plus extra for pressing dough
Finely chopped walnuts (or pecans or decorative sugar)
Directions
In a bowl of an electric mixer on medium-high speed, beat butter until creamy, about 1 minute. Gradually add sugar and beat until light and fluffy, about 2 minutes. Add egg yolk and beat until thoroughly combined. Reduce speed to low, add cinnamon and flour and mix until just incorporated. Cover with plastic wrap and refrigerate at least 1 hour.
When ready to bake, preheat oven to 350 degrees and line baking sheets with parchment paper. In a small bowl, slightly beat reserved egg white with a fork. Roll dough into small balls and place 2 inches apart on prepared baking sheets. Dip a flat-bottomed glass in flour and press dough to 1/16- to 1/8-inch thickness, re-flouring glass with each cookie.
Brush a little egg white in center of each cookie and sprinkle chopped walnuts (or pecans or decorative sugar) in center of cookie. Bake 10 to 12 minutes; do not overbake. Remove from oven, cool 2 minutes before transferring cookies to a wire rack to cool completely.
2009 Finalist: Ramona Doebler of Elk River, Minnesota