Preheat oven to 325 and prepare three 8″ round cake pans with parchment rounds and cooking spray.

For the Crisp:  First cut butter into flour and sugars until crumbly then stir in oats and salt.  Divide evenly and press into the bottom of the 3 prepared pans.  Bake for 10 minutes until golden and fragrant.  Set aside while preparing the cake batter.

For the Cake: Beat butter and sugar until light and fluffy- approximately 4-5 minutes.  Blend in eggs one at a time.  Add applesauce, buttermilk, and vanilla and mix until incorporated.  Add dry ingredients until well combined, then fold in grated fresh apple.  Spoon the cake batter evenly over the 3 crisp layers in the cake pans and bake for approximately 25 minutes.  Allow to cool for 5-10 minute in pans before turning out onto cooling rack and cooling completely.

For the Apple Filling: Peel, core, and dice the apples.  I like a small dice so the chunks of apple aren’t overwhelming.  Toss apples in a medium bowl with the sugars, cinnamon, salt, and cornstarch.  Melt 2 Tablespoons of butter in a skillet then add apples and saute about 4 minutes.  A gravy like cinnamon sugar sauce will form, and the apples should be slightly softened.  Let the filing cool to room temperature.

For the Caramel Sauce: Caramel is tricky, but once you get the hang of it there is no going back to the jar!  To avoid crystallization, I wet a medium saucepan with 2 Tablespoons of water.  Add the sugar and cook on medium high/high heat.  The sugar will start to liquify and brown.  As it brown, gently swirl the saucepan to even out the color.  When your sugar has reached a nice golden color and no sugar crystals remain, carefully add your butter and stir with a wooden spoon or spatula.  Once the butter has melted, add the heavy cream, being careful to avoid steam and splatters.  Reduce heat to low and cook for a minute or two while all the ingredients cook together and even out.  Set aside to cool.

For the Frosting: Blend the butter and cream cheese.  Add the caramel sauce, vanilla, pinch of salt and mix until well incorporated.  Add the powdered sugar and mix thoroughly.  I like a light and fluffy frosting, so I mix for at least 5 minutes.

To Assemble: With all components at room temperature, you can begin building your masterpiece.  Begin by piping a circle on the top of your first layer creating a dam to keep any filling from leaking out.  Spread half of the apple filling over the first layer.  Top with the next cake layer and repeat the process using the remaining apple filling.  Top with the third cake layer.  Spread a thin layer of frosting over the entire cake to create a crumb layer.  Since this cake has actual crumbs from the crisp layer, this step is very important.  Place your cake in the freezer for 10 minutes to chill the crumb layer.  At this point, you can use the remaining frosting to frost and decorate your cake.  Use the remaining caramel to top the cake, drizzling caramel down the sides, and sprinkle with some flaky sea salt.  Use apple slices, dried apples, cinnamon sticks, etc. for garnish and decoration.