On a cake stand or plate, place your first layer of chocolate cake (make sure to remove your parchment paper from your cake layers). Then place a heaping scoop of buttercream on top. Spread out your buttercream creating a well in the center.
In the center of your well, pour on about ½ of your remaining caramel. Do not overfill your well or it will pour out the sides and you will have a mess. It is ok if you have to use less than half of the caramel.
Then sprinkle on about half of your chopped nuts.
Repeat for the second layer, using up the remaining caramel and chopped nuts (you may have leftover caramel which is okay).
Top off your cake with your third layer of chocolate cake.
Using up about ⅓ of your remaining buttercream, frost on a crumb coat (a thin layer of frosting). Then place the cake in the fridge for about 30 minutes. Once your crumb coat is chilled and set, use the majority of your remaining frosting to frost your cake (you may want to leave some buttercream to the side for decoration). Use a spatula to smooth out your frosting.
Pour your chocolate ganache on top of your cake and use a spatula to smooth it out, letting the chocolate ganache drip over the edges creating a pretty drip look. Let the chocolate completely cool by placing the cake in the fridge for at least 30 minutes.
Using any remaining buttercream, pipe on a decorative edge and sprinkle on your remaining nuts for decoration!
Serve and enjoy!