Browned-Butter Shortbread

Made these for work on Sunday and they were a big hit. I promised to post the recipe, so here it is:

12 Tbsp. unsalted butter, slightly softened, divided*
1/2 cup sugar
1 3/4 cup flour
1/2 tsp. salt*

*Note-I used salted butter and left out the salt and it turned out just fine.

1.) In heavy 2qt. saucepan, melt half the butter over low heat. Cook 8-12 minutes, stirring occasionally, until butter solids at bottom of pan are a rich brown color and butter has a nutty aroma. (Browned butter can go from perfect to burned in seconds, so pay close attention to this and pull it off the heat as soon as you see it's ready.) Pour browned butter into a small bowl; refrigerate until almost firm, about 35 minutes.
2.) Preheat oven to 350 degrees. In large bowl, with mixer at medium speed, beat sugar with cooled browned butter and remaining softened butter until creamy.
3.) With hands, mix flour and salt into butter mixture just until crumbs form. Pat shortbread crumbs into ungreased 9" round cake pan or tart pan with removable bottom.
4.) Bake shortbread 40-45 minutes until browned around the edge. Let cool in pan on wire rack 10 minutes.
5.) Remove shortbread from pan to cutting board. While still warm, cut shortbread into 16 wedges. Cool wedges completely on wire rack. Store cookies in tightly covered container.
Makes 16 150 cal./9 g. fat per cookie