Brown Butter Pecan Shortbread

Grind pecans in processor until coarse meal forms. Melt 1/2 cup butter in small skillet over medium heat. Cook until dark amber, stirring often, about 6 minutes (do not burn). Pour through fine strainer into small bowl. Chill just until firm about 1 hour. Preheat oven to 300 degrees. Whisk flour and salt to blend. Using electric mixer, beat brown butter, 1/2 cup butter and sugar in large bowl until creamy. Beat in vanilla, then nuts. Gradually beat in flour mixture on low speed just to blend. Transfer dough to sheet of parchment paper. Form dough into rectangle. Place second sheet of parchment paper over dough. Press or roll dough into 12x8inch rectangle. Remove top sheet of parchment to baking sheet. Using fork, pierce dough all over, spacing 1 inch apart. Bake shortbread until golden brown and firm to touch, about 55 minutes. Leaving shortbread on baking sheet, cut lengthwise on baking sheet, cut lengthwise into 8 strips. Cut each strip crosswise into quarters. Cool 10 minutes minutes on sheet on rack. Transfer cookies to rack to cool completely.