Place the butter and sugar in a large bowl, beat on medium speed until light and fluffy. Add the eggs one at a time beating well after each addition. Stir in the vanilla. In a medium bowl combine the flour, baking soda, cinnamon and salt. Stir to combine. STIR the flour mixture into the butter/ sugar mixture until it is incorporated. I added the flour in 3 batches, making sure each batch of flour was incorporated before adding the next batch. Stir in the grated apples and chopped walnuts, stir until incorporated.