Cream butter and sugar, blend in egg. Measure flour by spooning into cup and leveling off or by sifting. Stir flour, cocoa and salt into butter mixture; blend well. Chill dough 1 to 2 hours press and mold into 2 long smooth rolls about 1 1/2" in diameter. Roll in chopped pecans pressing nuts into all sides. Chill overnight. Heat oven to 400 degrees cut into 1/8" slices. Place on ungreased baking sheet. Bake 10 min. Cool Melt chocolate in double boiler; frost center of cookies. Makes about 8 doz.