Preheat the oven to 350ºF and prepare three 6-inch or two 8-inch cake pans by spraying the sides with cooking spray and fitting the bottoms with a wax paper or parchment cake circle.

Place all of the dry ingredients into the bowl of a stand mixer and stir on low for 30 seconds to fully combine them. Add the vegetable oil, eggs, vanilla, and buttermilk and mix on low until just combined. With the mixer still on low, add the hot coffee (or hot water) in a slow stream, then turn the mixer to medium and beat until smooth, about 2 minutes. The batter will be very thin.

Pour into prepared cake pans no more than ⅔ full and bake for 35-40 minutes, until a wooden toothpick inserted comes out clean. Cool completely before filling and frosting.

Combine the sugars, corn syrup, butter, eggs, pecans, and salt in a medium saucepan and bring to a boil over medium heat, stirring constantly. Reduce the heat to low and simmer, stirring constantly for 6-8 minutes until the filling is thickened. Remove from heat and stir in the vanilla. Cool completely before using as filling. It will thicken and stabilize as it cools.

Have everything pre-measured and ready to go (you’ll be constantly stirring). Place the sugar in a medium saucepan over medium-high heat and stir constantly with a wooden spoon, until it melts into an amber-colored liquid and no sugar clumps remain, 5-6 minutes.

Reduce the heat to medium. Carefully add the butter (it will bubble up when you do) and use a whisk to combine it with the sugar mixture until the butter is fully melted and incorporated, 2-3 minutes.

Add the heavy whipping cream in a steady stream while whisking. As soon as the cream is incorporated, let the caramel boil for a full minute before removing it from the heat and stirring in the salt.

Let the caramel cool to room temperature before using as a filling or drip. It will thicken as it cools.

With a hand mixer or paddle attachment on your stand mixer, cream the butter and brown sugar on medium-high until it’s creamy, light, and homogenous. About 4 minutes.

With the mixer on low, add the powdered sugar a few cups at a time, scraping down after each addition and making sure each cup is fully incorporated before adding the next one.

Add vanilla, milk, and salt and mix on low for another minute until fully incorporated.

Once the Chocolate Cakes have cooled completely, level and torte each layer to your desired height. Place the first layer on a turntable and pipe a circle of Brown Sugar Buttercream around the edge. Fill in the center with (room temperature) Pecan Pie Filling about ¾ of the way to the top of the buttercream circle height-wise. Drizzle room temperature Salted Caramel on top of the Pecan Pie Filling. Here's a detailed tutorial on this filling method.

Place the next cake layer on top and repeat the process of piping the buttercream circle and filling in the center with Pecan Pie Filling and Salted Caramel. Place the final layer on top, upside down so that the bottom of the cake layer is the top of the cake. Crumb coat the cake with Brown Sugar Buttercream and place it in the refrigerator for at least 20 minutes to let everything set up.

To create the cake design pictured, frost a smooth layer of Brown Sugar Buttercream around the cake and place it back into the refrigerator for at least 30 minutes to create a cold foundation for the Salted Caramel drip. Meanwhile, microwave the Salted Caramel in 10 second increments until it's slightly warmer than room temperature and good drip consistency (this post shows examples of perfect drip consistency with Chocolate Ganache and those same rules apply to Salted Caramel drip consistency). When the cake is nice and chilled and the Salted Caramel is perfect drip consistency, drip the cake. Place it back into the refrigerator for 10 minutes to let the caramel set.

Create a design on the top of the cake with halved pecans. Prepare a piping bag with Wilton Tip 4B and fill it with Brown Sugar Buttercream. Holding the piping bag at a 45 degree angle pointed at the top of the cake, pipe a series of continuous swirls to create a rope border around the top edge.