Preheat your oven to 350°F (175°C) and prepare two 8-inch cake pans by greasing them with nonstick spray and lining the bottoms with parchment paper.

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

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

Create a well in the center of the dry ingredients and pour in the wet mixture, stirring gently until just combined. Add in the hot coffee and stir until smooth.

Pour the batter evenly into the prepared cake pans and bake for 30-33 minutes until a toothpick comes out clean.

Let the cakes cool in the pans for 10 minutes before transferring to wire racks to cool completely.

In a medium saucepan, combine fresh blackberries, sugar, lemon juice, lemon zest, cinnamon stick, and water. Cook over medium heat for about 5-6 minutes, stirring gently.

Mix cornstarch with 1 cup of water to create a slurry, then add to the saucepan and cook until thickened for 2-3 minutes.

Set aside the compote to cool completely.

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

Level the cooled cake layers if necessary. Place one layer on a cake stand and spread blackberry compote on top, then add the second layer.

Frost the outside of the cake with remaining cream cheese frosting and decorate with chocolate skulls, fresh blackberries, and crushed dried rose petals.