Cream together 4 oz butter, 2oz sugar & 1/4 tsp vanilla essence. Add 1 cup flour, 1 tsp baking powder & 3 Tbs chopped walnuts. Spread in flat tin & bake 15 mins moderate oven. Ice while warm.
Icing: Bring to boil 2 oz butter, 1 cup icing sugar & 2 Tbs condensed milk.