Mix 1 C. flour, 1/2 C. softened butter and 1 C. finely chopped pecans and pat into 9 x 13″ pan. Bake for 15 – 20 minutes; remove from oven; cool. Whip together 8 ounces cream cheese and one C. powdered sugar. Fold in half a 9 oz. container of cool whip. Spread over cooled crust. Combine 1 6 3/4 oz package of instant chocolate pudding with 1 6 3/4 ounce package of instant vanilla pudding. Beat in 3 C. cold milk until smooth and thickened. Layer over the cream cheese. Spread remaining cool whip on the top. Grate a chocolate candy bar and sprinkle over the cool whip. Refrigerate overnight.