Line an 8×8 baking dish with parchment paper or aluminum foil, extending pieces over sides for easy handling. If using foil, spray with cooking spray. Set dish aside.

Place each color of candy melt in its own microwave-safe bowl. Microwave for 30-second intervals, stirring in between, until candy is smooth. Set bowls aside.

Remove lid and foil seal from vanilla frosting, then microwave on high for 35 seconds or until frosting has completely melted.

Divide and pour frosting evenly between each bowl of melted candy. Add red food coloring to white candy and black food coloring to dark chocolate, then mix well until combined. Add more food coloring as needed to achieve the desired hue.

Alternating between two colors, pour fudge mixture into prepared baking dish. If desired, drag a toothpick or butter knife through colors once or twice to create a swirl pattern. Tap baking dish lightly on counter to level fudge mixture into an even layer.

Cover dish with plastic wrap and chill in refrigerator for at least 1 hour or until set.

Lift fudge out of baking dish by gripping excess paper/foil along sides, then transfer fudge to a work area. Peel back paper/foil from edges of fudge, then cut fudge into 2-inch squares or cut with festive cookie cutters.

Serve as desired.