2 sticks butter, softened 1/2 cup granulated sugar 1/2 teaspoon salt 1 egg yolk 2 1/4 cups all-purpose flour 1/3 cup chopped candied or maraschino cherries, well drained Red food coloring 1/4 cup finely chopped pistachio nuts 1 1/2 ounces semisweet chocolate melted, slightly cooled In large bowl, with electric mixer, cream butter, sugar, salt and egg yolk until smooth. Gradually beat in flour. Wrap dough in plastic wrap; refrigerate 1 hour or up to 2 days During this time, the flavors blend and develop, bringing out the butter flavor of the dough. Divide dough into thirds. Leave one third of the dough plain. Into one portion add cherries and 4 to 5 drops of red food coloring. To remaining portion mix in nuts and chocolate. Line bottom and sides of an 8 1/2- by 41/2-inch loaf pan with waxed paper or plastic wrap. Press plain portion of dough into bottom of pan. Refrigerate for about 10 minutes, or until dough is firm. Top with cherry layer. Refrigerate again if necessary to firm dough. Top with final chocolate layer. Cover pan and refrigerate at least 3 hours or up to 2 days. Preheat oven to 350°. Remove dough from pan. Cut dough lengthwise in half. Cut each half into 1/2-inch slices. Place cookies 1 inch apart on ungreased cookie sheet. Bake about 11 to 13 minutes, until edges are lightly browned.