Preheat oven to 300 degrees F (150 degrees C). Grease and flour a tube pan.
Whisk together flour, salt, cinnamon, cloves, and soda. Set aside.
Cream together 1/2 cup butter and 2 cups brown sugar, beating until light and fluffy. Mix in eggs. Add flour mixture into creamed mixture alternately with applesauce, beginning and ending with flour mixture. Stir in the raisins, dates, and walnuts. Pour batter into prepared pan.
Bake in preheated oven until a tester inserted in the center of the cake comes out clean, about 1 1/2 hours. Cool on wire rack.
To make icing, melt 1/2 cup butter or margarine in a small saucepan over low heat; stir in 1 cup brown sugar. Boil for 2 minutes. Stir in milk, and continue to stir until the mixture returns to a boil. Remove from heat, and cool for 5 minutes. Beat in vanilla and confectioners' sugar. Frost cooled cake.