Prepare the Chocolate Cake

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and flour a skull-shaped cake pan.

2. Combine Dry Ingredients: In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt until well combined.

3. Mix Wet Ingredients: Add the eggs, milk, vegetable oil, and vanilla extract to the dry ingredients. Beat on medium speed for 2 minutes until smooth.

4. Add Boiling Water: Carefully stir in the boiling water. The batter will be thin.

5. Pour into Pan: Pour the batter into the prepared skull-shaped cake pan, filling it about ¾ full.

Bake the Cake

1. Bake: Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean.

2. Cool: Allow the cake to cool in the pan for 10 minutes before inverting onto a wire rack to cool completely.

Make the Chocolate Ganache

1. Heat the Cream: In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer.

2. Add Chocolate: Remove from heat and add the chopped dark chocolate. Let sit for 5 minutes, then whisk until smooth and glossy.

3. Cool: Allow the ganache to cool slightly before using.

Assemble the Cake

1. Level the Cake: If the cake has domed, level the top with a serrated knife to create a flat surface.

2. Apply Ganache: Pour the chocolate ganache over the cooled skull cake, using a spatula to spread it evenly over the top and sides.

3. Decorate: While the ganache is still soft, place the candy eyes on the skull and use Halloween candies to create additional features, such as a mouth or nose.

4. Optional Finishing Touch: For a sparkly effect, lightly dust the cake with edible gold dust or shimmer spray.