For the Chocolate Cake
Preheat the oven to 360 degrees F. Prepare three 8-inch round cake pans by spraying the bottom and sides with nonstick spray, lining the bottom with parchment paper and spraying again. Set aside.
In a bowl of electric mixer, combine and stir all dry ingredients. Set aside.
In medium sized mixing bowl, combine eggs, buttermilk, water or coffee, oil and vanilla and beat lightly with a fork.
With the mixer on low speed, add wet ingredients to the dry ingredients, and mix until incorporated (about 30 to 60 seconds). Batter will be thin. Scrape sides and mix for another 30 seconds. Divide batter evenly among prepared pans (I like to use a kitchen scale to ensure the batter is evenly distributed - about 15 to 16 ounces of batter in each 8-inch pan.
Bake for 16-20 minutes, until toothpick comes out with a few moist crumbs on it. Cool on wire racks for 10-15 minutes, then gently invert onto racks until cooled completely.
When cakes are completely cooled, divide each cake layer into two with a cake leveler so you have six layers total. Keep the two layers together (for each of the three cake layers you baked) and wrap with plastic wrap and freeze until you're ready to use. The cake will be easier to work with if it’s cooled a bit. Let thaw for about an hour before frosting.
For the Chocolate Caramel Frosting
Put the chocolate into a mixing bowl and pour the warm caramel sauce over the chocolate. Stir until the mixture is smooth and starts to cool down.
After it cools down a bit, add the butter, little by little, beating until everything is smooth and well blended.
The frosting is done when the texture is soft and silky. If you added the butter while the mixture was still warm, just place the bowl in the refrigerator for 15-20 minutes to set. Continue beating for another 5-7 minutes until it reaches a thicker, more spreadable consistency as seen in the picture above.
If the buttercream is still too soft, place in the refrigerator again for a couple hours and then re-beat when you're ready to use.
For the Caramel Sauce
Mix sugar, water and corn syrup in a small saucepan.
Bring the water and sugar mixture to boil over medium heat, but DO NOT STIR. (Stirring encourages crystallization). Let the mixture cook until it caramelizes into a golden brown color. It happens quickly, so keep an eye on it.
Remove the caramelized sugar syrup from the heat and slowly mix in the cream. Pour in just a tiny bit at a time, especially at the beginning, and mix to combine. You can start adding more and more as you go along.
Mix in salt and vanilla. Stir to combine.
NOTE: You'll use one cup of caramel sauce for the frosting and will need to reserve 1/2 cup for the drizzle. Make sure the caramel sauce for the drizzle is at room temperature before piping on the cake.