Preheat oven to 350 degrees. Sift flour, cocoa, baking soda and salt onto wax paper. Beat butter, sugar, eggs and vanilla in a medium-size bowl with electric mixer until fluffy. Stir in dry ingredients; beat until smooth. Fold in 1/2 cup of the chopped nuts. Pour into greased 13x9x2 inch pan. Bake in preheated 350 degree oven for 30 minutes. Remove pan from oven to wire rack; sprinkle with peanut butter chips. Let stand about 5 minutes, then spread evenly with a small metal spatula. Sprinkle with remaining nuts, patting down gently. Cool; cut into bars Recipe By :