Preheat oven to 350 degrees.
Cream together 1 c. butter and sugar.
Add eggs and 3 tsp. vanilla and mix.
Combine flour, cocoa, salt, baking powder and baking soda.
Add flour mixture to creamed mixture until completely incorporated.
Roll into balls and place on parchment paper covered cookie sheet. Flatten balls with palm of hand.
Bake for 10-12 minutes. Cool.
Mix together cream cheese, 1/2 stick butter and 1/2 tsp. vanilla. Add powdered sugar to spreading consistency.
Ice cooled cookies and top each with a walnut half. Makes 6 dozen.