Preheat the oven to 350 degrees F. Line 3 8-inch cake pans with parchment paper and then spray with non-stick cooking spray, set aside.

In the bowl of a stand mixer with the paddle attachment, stir together the flour, baking powder, salt, and baking soda.

In a large bowl, whisk or beat with an electric hand mixer together the brown sugar, oil, eggs, buttermilk, melted chocolate, and vanilla.

With the mixer on low, slowly add the wet ingredients to the dry ingredients until combined, making sure to scrape down the side.

With the mixer still on, slowly pour in the boiling water slowly until mixed in well.

Evenly divide the batter among the cake pans.

Bake for 30-35 minutes until a toothpick inserted into the center comes out clean. Remove the cakes from the oven and let the cakes cool completely in the pans on a wire rack.

While the cakes are cooling, first make the caramel pecan frosting.

Add the butter and brown sugar to the bowl of a stand mixer fitted with the paddle attachment and beat together for about 3 minutes until combined and fluffy.

Add in the powdered sugar a little at a time until fully mixed in. Then add the milk, vanilla, and salt, beat in until combined, then beat on medium-high speed for 3 minutes until fluffy.

Lastly, fold in the pecans until mixed in well and set aside.

For the chocolate frosting, in the bowl of a stand mixer fitted with the paddle attachment, add the butter and melted chocolate and stir to combine.

Add the powdered sugar a little at a time until mixed in. Then add the milk, vanilla, and salt, and mix until just combined. Place the mixer on medium-high and again beat for 3 minutes, until light and fluffy.

Take out one of the cakes discarding the parchment paper. Place it on a cake stand or serving platter and trim the cake dome if necessary.

Take a fork and gently poke holes into the top of the cake.

Add ⅓ of the caramel sauce and spread it over the cake so the cake absorbs the caramel.

Next, add ½ of the caramel pecan frosting and spread it out to the edge of the cake.

Add another cake layer on top, again poke the top of the cake with holes and add another ⅓ of the caramel, spreading it out.

Add the remaining caramel pecan frosting, and smooth it out to the edge.

Then, add the last cake on top, again poke the cake with holes and add the last of the caramel, spreading it out.

Crumb coat the entire cake with about half of the chocolate frosting. Then place in the refrigerator for at least 2 hours or up to overnight to set up.

Once set, add the remaining chocolate frosting all over the outside of the cake.

Decorate with more chopped pecans and add a drizzle of caramel if desired. Allow the cake to come to room temperature before slicing and serving.