To make the topping, in a small bowl mix the sugar, cinnamon and finely chopped walnuts. Set aside.
In a medium bowl combine flour, salt, baking powder, baking soda, cinnamon, and nutmeg. Set aside.
In a separate large bowl cream butter and sugar. Add eggs and vanilla extract, and mix well. Gradually beat in flour mixture alternately with buttermilk. Stir in apples, walnuts, and semi-sweet chocolate chips. Pour into a greased 9x5x3 inch loaf pan. Sprinkle with topping.
Bake in a preheated 350 degree F (175 degree C) oven for 50 to 60 minutes. Cool for 15 minutes. Remove from pan. Cool on a wire rack.