01 - Preheat oven to 350°F. Grease and line two 8-inch cake pans with parchment paper.
02 - In a large bowl, whisk together flour, black cocoa powder, sugar, baking powder, baking soda, and salt until well combined.
03 - Add vegetable oil, milk, eggs, and vanilla extract to the dry mixture. Mix until just combined, then stir in hot water until batter is smooth.
04 - Divide batter evenly between prepared pans. Bake for 35 to 40 minutes or until a wooden pick inserted in center comes out clean. Cool completely in pans before removing.
05 - Combine cherries, sugar, and lemon juice in a saucepan. Simmer over medium heat for 5 to 7 minutes. Whisk cornstarch with water, add to cherries, and cook until thickened. Cool completely.
06 - Heat heavy cream until just simmering. Pour over chopped dark chocolate and black cocoa powder. Let stand for 3 minutes, then whisk until smooth. Add black food coloring gel if deeper color desired.
07 - Place one cooled cake layer on serving plate. Carefully hollow out a shallow circle in center of cake, leaving border intact.
08 - Fill cavity with cooled cherry compote. Place second cake layer on top, pressing gently to seal.
09 - Spread black cocoa ganache evenly over top and sides of cake. Refrigerate until ganache is set, about 15 to 20 minutes.
10 - Pipe red food coloring gel in vein-like patterns on cake surface. Create edible spiders with fondant or melted chocolate. Add edible glitter for spooky effect.