Salted Maple Thumbprint Cookies

 3 cups all-purpose flour
 1 teaspoon kosher salt
 1 cup (2 sticks) unsalted butter, room temperature
 1 cup sugar
 1 cup pure maple syrup
 2 large egg yolks
 12-ounces walnut halves
 Fleur de sel or other coarse salt, for sprinkling (optional)
 

Preheat oven to 350 degrees F. In a medium bowl, whisk together flour and kosher salt. In the bowl of an electric mixer fitted with a paddle, cream together butter and sugar until light and fluffy. Scrape down the sides of the bowl, add 1/2 cup of the maple syrup and the egg yolks, and beat until fully incorporated. Add the flour mixture and mix until just combined. Chill dough for 30-60 minutes.

Using a tablespoon, drop dough, 3 inches apart, onto two baking sheets. Using your thumb, make an indentation in the center of each round of dough – as deep as you can go without pushing through. Bake until the edges are just golden, 12-15 minutes. Transfer to a wire rack and cool.

While the cookies are cooking, prepare the maple glaze. Place the remaining 1/2 cup maple syrup in a small saucepan over medium heat. Simmer the syrup until reduced to about 1/3 cup, 7-10 minutes. Carefully spoon the glaze into the thumbprint of each cooled cookie, then place a walnut and a sprinkle of salt on top. Allow the glaze the set, at least 10 minutes, before serving.

Recipe Source: http://www.csmonitor.com/The-Culture/Food/Stir-It-Up/2010/1204/In-honor-of-National-Cookie-Day-Salted-maple-thumbprint-cookies