Cookie Mixture:

1 c. flour
3/4 tsp. salt
1/4 tsp. baking powder
1/2 c. brown sugar
1/4 c. soft butter
1 egg yolk
1/2 tsp. vanilla

Filling Mixture:

6 oz. chocolate chips (semi-sweet)
1 tbsp. shortening
1 c. chopped walnuts
1/3 c. sweetened condensed milk
1 tsp. vanilla
1/4 tsp. salt

Mix flour, salt and baking powder. Blend brown sugar and butter. Beat in egg yolk and vanilla. Stir in flour mixture. Roll on floured board to 9 x 12 rectangle.

Melt chocolate chips with shortening. Stir in nuts, sweetened condensed milk, vanilla and salt. Mix until well blended. Press evenly over dough. Roll up and wrap in aluminum foil. Freeze or refrigerate until firm. Cut into 1/2-inch slices. Place on cookie sheets and bake at 375°F for 10 minutes.