Preheat your oven to 350°F (175°C). Coat two 8-inch round cake pans with nonstick spray and line the bottom with parchment paper.

In a large mixing bowl, sift together the all-purpose flour, black cocoa powder, granulated sugar, baking powder, baking soda, and salt.

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

Create a well in the center of the dry ingredients and pour in the wet mixture. Fold together until just combined, then stir in the hot coffee.

Divide the batter evenly between the prepared pans. Bake for 30-33 minutes, or until a toothpick comes out clean.

Allow the baked layers to cool in the pans for about 10 minutes. Then, transfer them to wire racks to cool completely.

In a saucepan, combine fresh blackberries, granulated sugar, lemon juice, and a cinnamon stick. Cook until the blackberries break down, then mix in the cornstarch slurry and cook until thickened.

In a mixing bowl, beat cream cheese and butter until smooth. Gradually add sifted powdered sugar and cocoa powder until fluffy.

Level the cooled cake layers and spread blackberry compote on top of the first layer. Place the second layer on top and apply a thin crumb coat of frosting.

Decorate the top of the cake with chocolate skulls, fresh blackberries, and dried rose petals.