Pour the cup of boiling water over the cup of dates and the tsp.of soda. Let cool. Cream the sugar and margarine and add the beaten egg.Then add the date mixture and vanilla. Add the flour salt mixture and nuts. Pour into greased and floured 8 inch square pan and bake in 350 oven 35 min. In saucepan put 5 tblsp. brown sugar, 5 tblsp. whole milk or cream and 2 tblsp. margarine. Bring to a boil and boil 3 minutes. Remove from heat and cool to lukewarm then add icing sugar to thickness desired for spreading.