Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a large bowl, combine the sugar, flour, black cocoa powder, baking soda, baking powder, and salt. Whisk these together until they are all mixed well.

In another bowl, whisk together the eggs, buttermilk, hot coffee, canola oil, and vanilla extract.

Slowly pour the wet ingredients into the dry mixture. Mix until everything is smooth and well combined.

Divide the batter evenly between the two prepared pans. Bake for about 30-35 minutes, or until a toothpick inserted into the center comes out clean.

Once baked, let the cakes cool in the pans for about 10 minutes. Then remove them and let them cool completely on wire racks.

In a medium saucepan, combine fresh blackberries, white sugar, lemon juice, lemon zest, cinnamon stick, and water.

Cook over medium heat until the blackberries break down, about 10 minutes, stirring occasionally.

In a small bowl, mix cornstarch with a little water to create a slurry. Add this to the blackberry mixture and cook for another 2-3 minutes, until it thickens. Remove from heat and let it cool.

In a bowl, beat softened cream cheese and unsalted butter together until smooth and creamy.

Gradually add the sifted powdered sugar, black cocoa powder, salt, and vanilla extract. Mix until fluffy.

If the frosting is too thick, add a little milk until you reach the desired consistency.

Place one cake layer on a serving plate. Spread a layer of blackberry compote over it.

Place the second cake layer on top.

Use the black cocoa frosting to cover the top and sides of the cake.

Add chocolate skulls, fresh blackberries, and dried rose petals on top of the frosting for a spooky look.