• Grease three 8 inch (20cm) round cake pans and line with parchment paper.

Prepare the walnut crunch.

• In a small saucepan add sugar, whipping cream and butter. Cook over medium-low heat until sugar dissolves.
• Divide the mixture evenly in two pans. Sprinkle chopped walnuts/pecans on top. Set aside until apple cake batter is prepared.

Prepare apple cake layers.

• Preheat oven to 350F (180C). In a medium bowl whisk the flour, baking powder, baking soda, salt, and cinnamon. Set aside.
• In a large bowl add eggs with both sugar and mix for few minutes until creamy and lighter in color. Add oil and mix until well combined. Add vanilla extract. Gradually mix in flour mixture. Using a spatula incorporate the apple pieces.
• Pour the batter evenly into the prepared pans.
• Bake for about 20-25 minutes until a toothpick inserted into the center comes out clean.
• Let pans cool on a cooling rack.

Prepare dulce de leche buttercream.

• Both butter and dulce de leche need to be at room temperature before preparing the frosting.
• In case you can not find dulce de leche in stores you can always prepare it in advance using cans of sweetened condensed milk. Place the unopened and unlabeled can of sweetened condensed milk in a saucepan, and cover with water. Place the saucepan over medium-high heat and bring to a boil. Cook for 2.5- 3 hours. Remove from heat, remove the can from water and cool.
• In a large bowl mix butter until light and fluffy, for about 5-7 minutes.
• Incorporate vanilla extract. Gradually add dulce de leche, mixing after each addition. Once incorporated the buttercream is ready to use.

Assemble the cake.

• Place one cake layer on your serving plate with walnut crunch on top. Spread evenly with a bit less than a third of buttercream. Add the second layer of cake with walnut crunch on top. Spread evenly with bit less than a third of buttercream. Add the last layer of cake. Spread the top and edges with the remaining buttercream. Decorate the bottom of the cake with chopped nuts. Refrigerate to set for at least 1 hour.

Prepare caramel shards.

• Spread chopped walnuts/pecans on a parchment paper lined baking sheet.
• Place water and sugar into a small saucepan and cook over medium heat until sugar dissolves and gets a caramel dark color.
• Pour the caramel over the chopped nuts and refrigerate until ready to use.

Prepare the caramel sauce.

• Place the sugar and water in a medium heavy-bottomed saucepan over medium-high heat, and cook without stirring until sugar dissolves and gets a caramel color.
• Remove the pan from the heat and add the cream. It will bubble a little bit.
• Cook for about 1 minute stirring constantly with a wooden spoon until smooth.
• Remove from heat and add butter, vanilla, and salt. Stir well until smooth. Pour into a bowl to cool slightly.
• Use a spoon and start making drips around the edges. If the sauce hardened too much heat it a bit over bain-marie to get to a pouring consistency.
• Top the cake with remaining caramel sauce and spread using an offset spatula.
• Refrigerate to set for at least 30 minutes.
• Break caramel into shards and decorate the cake. Enjoy. Refrigerate leftovers.