Preheat your oven according to the instructions on your cake mix box. Grease and flour two 9-inch cake pans. Pour the prepared cake batter evenly into each pan. Bake the cake as directed until a toothpick comes out clean. Once baked, allow the cakes to cool completely in the pans before transferring them to a wire rack.

Once the cakes are completely cooled, place one cake layer on a serving plate. Spread a generous amount of chocolate ganache over the top. Place the second layer on top and press down gently to secure.

Using the remaining ganache, spread it smoothly around the sides and over the top of the cake. Make sure to cover it completely for a neat finish. If the ganache is too thick, you can slightly warm it to achieve a smoother consistency.

To make the cake visually stunning, warm a small portion of extra ganache in the microwave. Using a spoon or a squeeze bottle, drizzle it over the edges of the cake, allowing some to drip down the sides.

Fill a piping bag with the melted white chocolate. Start at the center of the cake, and carefully drizzle it in a spiral pattern outward. This will form the base of your spiderweb design.

Using a toothpick or skewer, gently drag it from the center of the cake out towards the edges, creating lines to mimic a spiderweb. Finally, place your plastic spider rings in different spots on top of the cake for a fun Halloween finish.