1
Preheat your oven to 350°F (175°C). Prepare two 8 x 3-inch round cake pans by spraying them with non-stick spray and lining the bottoms with parchment paper.
2
In a large bowl, whisk together the all-purpose flour, unsweetened cocoa powder, and salt until well combined.
3
Using an electric mixer fitted with the paddle attachment, blend the canola oil and granulated sugar together at medium speed until they are well mixed. Add the eggs, one at a time, ensuring each is fully incorporated before adding the next.
4
With the mixer on low speed, slowly stream in the red food coloring and vanilla extract, taking care as the red color might splash. Alternately add the dry flour mixture and buttermilk to the batter in two batches, starting and ending with the flour mixture. Scrape down the sides of the bowl as needed until everything is combined.
5
In a small bowl, mix the baking soda and white vinegar until they fizz, then immediately add this to the batter with the mixer running. Beat for an additional 10 seconds.
6
Pour the batter evenly between the prepared cake pans and bake for 30 to 40 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool completely once baked.
7
To make the frosting, beat the unsalted butter in a stand mixer with the paddle attachment until softened. Gradually add the powdered sugar, followed by the cream cheese, kosher salt, and vanilla extract. Continue to beat until the mixture is light and fluffy, which should take about 5 minutes.
8
Level the cooled cakes by cutting off the domed tops, saving the scraps. Divide each cake horizontally into two even layers. Using a 3 or 3½-inch cookie cutter, cut out the center of two layers, keeping the scraps for later.
9
Place one whole cake layer on a serving plate and apply a thin layer of cream cheese frosting. Place the second whole layer on top, then pipe or spread a ring of frosting around the outside edge of this layer. Add one holed layer on top of this.
10
Pipe or spread a thin layer of frosting inside the ring, then place the second holed layer on top. Carefully apply a thin coat of frosting around the entire cake and refrigerate.
11
Line a medium-sized bowl with plastic wrap, allowing excess to hang over the edges. Add a little frosting to the bowl, spreading it up the sides. Fill the bowl with cake scraps, layering with frosting as needed. Make a hole in the center that aligns with the holes in the layer cake.
12
Freeze the bowl for about 3 hours until firm. Refrigerate the layered cake separately.
13
Remove the dome-shaped cake from the freezer and unwrap the plastic wrap.
14
Fill the cake layer holes with the assorted candies. Spread a thin layer of frosting around the top edge of the ring to support the overlaying dome.
15
Carefully place the dome over the filled cake, using a piece of cardboard or a flat surface to flip it upside down if necessary to prevent candy spillage.
16
Frost the entire cake smoothly with the remaining cream cheese frosting, and refrigerate once more until firm.
17
For the fondant decoration, roll black fondant to ¼ inch thick and use cookie cutters to create eyes and a mouth, applying black sanding sugar for texture.
18
Dust your work surface with cornstarch to roll out a large piece of white fondant to ¼ inch thickness and ensure it forms a circle large enough to drape over the cake, about 16 inches across.
19
Carefully drape the white fondant over the cake, creating ghostly pleats by letting it drape naturally.
20
Use a small amount of water to attach the fondant facial features securely.
21
Refrigerate the completed cake until serving time.