Begin by lining an 8x8 baking dish with parchment paper or foil, allowing excess to hang over the sides for easy removal later. Set aside.

In separate bowls, microwave the white and dark chocolate candy melts in 30-second intervals, stirring in between until smooth.

Microwave the vanilla frosting for around 45 seconds until melted, then divide it equally between the two bowls of chocolate and stir to combine.

Add several drops of red oil food coloring to the white chocolate mixture, and black oil food coloring to the dark mixture; mix until colors are achieved.

Pour the colored mixtures alternatively into the prepared baking dish to create a marbled effect, then swirl with a toothpick.

Cover with plastic wrap and refrigerate for at least 1 hour or until set.

Once set, lift the fudge out of the dish and cut into squares or use cookie cutters for spooky shapes.