Preheat oven to 350°. Sift SWANS DOWN Cake Flour then lightly spoon into measuring cup for 2 ½ cups + 4 tablespoons. Sift together flour, salt and baking soda and set aside. In separate bowl, combine Heath Bar pieces and chopped walnuts, set aside. Beat together butter and sugar. Beat in eggs one at a time; add vanilla. Alternately add Heath bar mixture and flour mixture, a third at a time, until well blended. Chill dough for at least 30 minutes to 1 hour.
On cookie sheets lined with parchment paper, spoon out cookie dough in small 1 inch diameter balls (size of a large marble). Place dough balls away from each other on the cookie sheets making sure there is plenty of room between the cookie balls and that the cookie balls are not too big. These cookies spread! Bake for 10-12 minutes, until edges are just starting to brown. Remove from oven and let cool for a few minutes. Transfer to a wire rack to cool completely.