Preheat oven to 325°F. Butter two round cake pans (I used 8 inch) generously, then dust with cocoa powder, knocking out excess.

Heat coffee, buttermilk, rum, butter, and cocoa powder in a medium heavy saucepan over moderate heat, whisking, until butter is melted. Remove from heat, then add sugar and whisk until dissolved, about 1 minute. Transfer mixture to a large bowl and cool 5 minutes.

While chocolate mixture cools, whisk together flour, baking soda, and salt in a bowl. Whisk together eggs and vanilla in a small bowl, then whisk egg mixture into cooled chocolate mixture until combined well. Add flour mixture and whisk until just combined (batter will be thin and bubbly).

Pour batter into pans and bake until a wooden pick or skewer inserted in center comes out clean, 50 to 60 minutes.

Cool cake completely in pans on a rack, about 2 hours. Loosen cake from pans using tip of a thin knife, then invert rack over pan and turn cake out onto rack.

Put pecans and sugar and a splash of rum in a saucepan, mix thoroughly and place over medium heat.

Stir until sugar is completely melted and caramelized, taking care not to scorch the pecans. Be careful and watch constantly - the sugar quickly goes from granulated to melted.

Pour the caramelized mixture onto a sheet of parchment paper (or silicone mat) and spread it out flat using a rubber spatula. Allow to cool completely until hardened.

Break into small pieces, place in a food processor or blender and crush into a fine powder, then process until a smooth paste is formed (about 5 minutes).

Melt the chocolate in a heat-proof bowl set over a pan of barely simmering water.

Remove from heat. Add the butter and praline paste and mix well, then add the cream, stirring thoroughly.

Allow the ganache to set and cool completely. If necessary, place in the refrigerator for a few minutes.

Whip the butter with electric beaters to cream it. Add the sugar by a cup at a time beating until all of the sugar is dissolved. Add the rum, then enough whole milk 1 tablespoon at a time until the frosting is the consistency you want.

On a cardboard cake round set on top of a cake turn, set the first cake layer leaving the flattest side up. Spread all of the cooled praline ganache on top of the first layer. (if you so desire, you can also torte both layers by cutting them in half with a serrated knife and splitting the filling between three layers of filling - I chose to be lazy ;)).

Next, set the second cake layer on top of the ganache filling again leaving the flattest side up.

Using a large offset spatula spread a thin crumb coat layer of buttercream over the entire cake filling and leveling the sides. Set in the fridge to set for at least 1 hour or until frosting is firm to the touch.

Using your offset spatula again, frost cake with remaining buttercream.

With a piping bag fitted with either a large star or drop flower tip (ateco 823 or wilton 2C), pipe a decorative edge along the bottom. Start by piping a small dollop and then pulling gently with your hands away and down to form a scroll/ribbon shape. Continue along the entire edge.

Find a simple graphic shape and print it out. I just found a simple octopus shape. Cute it out using an exacto knife, saving any inside pieces. Lay the paper with the interior cut-out on top of the cake and cover any exposed icing with parchment paper to protect it. Ensure to lay any interior cut-out pieces back into the decal. Then dust with cocoa powder using a fine sieve. Gently remove the paper and using tweezers any small interior cut-outs.