1 cup (2 sticks) unsalted butter or margarine, room temperature
1 cup packed light brown sugar
1 egg yolk
1 teaspoon vanilla extract
2 cups all-purpose flour
1 cup (6 ounces) semisweet chocolate pieces
1 cup chopped walnuts
Preheat oven to 350 degrees.
Line a 15- by 10-inch jelly-roll pan with foil. In a medium bowl, beat together butter or margarine, brown sugar, egg yolk and vanilla until light and fluffy. Add flour, beating until well blended. Spread mixture evenly in foil-lined pan. Bake 15 to 18 minutes or until golden.
Sprinkle chocolate pieces evenly over cookie surface. Bake 2 to 3 minutes or until chocolate melts. Remove from oven and let stand 1 minute. With a knife, spread melted chocolate evenly over top.
Sprinkle with walnuts. While warm, cut into squares. Cool in pan. Store in refrigerator, if desired.
Makes about 54 cookies.
From Natalie Haughton, food editor, Los Angeles Daily News