First, make the chocolate cake. Preheat the oven to 350°F and grease and line 3 6 inch rounds or 2 8 inch rounds with parchment paper on the bottom. Set aside.
In a large bowl, whisk together sugar, cocoa powder, flour, baking soda, baking powder, and salt. In a separate bowl, whisk oil, vanilla, eggs, and buttermilk.
Pour the wet ingredients into the dry, whisking until no lumps remain. Pour in brewed coffee, mixing until just combined.
Pour batter into prepared pans and bake for roughly 30 minutes, or until a knife inserted in the center of the cake comes out clean. Cool completely on a wire rack before frosting.
While the cakes cool, make the homemade caramel. Prepare the caramel according to directions and allow to cool completely. Reserve 1/3 cup of the caramel for drizzling on top fo the finished cake and place the remaining caramel in bowl. Add the chopped pecans to remaining caramel and stir to combine. Transfer to a piping bag and set aside.
Next, make the frosting. Place the room temperature butter in a stand mixer fit with the whisk attachment. Beat the butter until creamy.
Scrape down the bowl and add the cocoa powder. Beat on low speed and gradually increase to high speed until homogenous.
Scrape down the bowl and add the powdered sugar, vanilla extract, espresso powder and 3 Tablespoons of milk to start. Beat on low speed and gradually increase to high speed, beating until light and fluffy.
To assemble the cake, place the first layer on a cake stand or flat plate. Pipe about half of the caramel filling around the cake. Place the second layer on top of the filling and repeat with the remaining half of the filling. Frost the cake with the chocolate frosting, covering the top and pulling down to cover the sides of the cake. Put the cake in the fridge to chill for 15 minutes. This will help the frosting and filling to set.
While the cake is chilling warm up the remaining 1/3 cup of caramel in a microwave safe bowl. Pour over the top of the cake, letting it drip down the sides. Top the top of the cake with crushed up pecans. Enjoy!