Preheat your oven to 350°F (175°C). Spray two 8-inch round cake pans with nonstick spray, then line the bottoms with parchment paper.

In a large mixing bowl, sift together flour, black cocoa powder, granulated sugar, baking powder, baking soda, and salt. Set aside.

In a separate bowl, whisk together buttermilk, canola oil, eggs, and vanilla until combined.

Create a well in the dry ingredients and pour in the wet mixture. Stir gently, then add hot brewed coffee and mix until smooth.

Evenly divide the batter between the pans and bake for 30-33 minutes or until a toothpick comes out clean. Cool in pans for 10 minutes, then transfer to a wire rack.

In a medium saucepan, combine blackberries, sugar, lemon juice, cinnamon stick, and lemon zest. Cook over medium heat until boiling, then add cornstarch mixed with water and cook until thick.

In a mixing bowl, cream together softened cream cheese and butter until smooth. Gradually add powdered sugar and black cocoa powder, blending well. Stir in vanilla extract.

Level cakes if needed. Spread a thin layer of frosting on serving plate, then layer the first cake. Pipe frosting along the edge and fill with blackberry compote. Place the second layer upside down.

Apply a crumb coat around the cake to seal crumbs, refrigerate for 20 minutes. Generously frost the cake and garnish with fresh blackberries, chocolate skulls, and optional dried rose petals.