Preheat oven to 350
Butter and flour a 9 x 13" pan
Whisk together the flour, salt, baking powder, baking soda, and cinnamon in a large bowl. Set aside.
in a stand mixer with the paddle attached beat the butter and sugar on high until light and fluffy.
Turn to low and mix in the eggs, one at a time followed by the vanilla.
Add the flour mixture and stir on low until just combined.
With the mixer on slow, mix in the grated apple.
Stir in the raisins.
Add the batter to the prepared pan and bake in the preheated oven for about 55 minutes until a toothpick comes out clean.
Cool on a wire rack for about 10 minutes.
While the cake is cooling, toast the walnuts either in a pan on top of the stove or in the oven.
Warm the caramel sauce and pour over the top of the warm cake. Spread it evenly over the top.
Sprinkle with the toasted walnuts.