Preheat your oven to 325℉ (163℃). Line a baking sheet with parchment paper.
Spread the cake mix over the parchment paper, smoothing it out in a level layer from edge to edge. Bake for 7-10 minutes, then set aside to cool completely.
1 boxed white or vanilla cake mix
Transfer the cooled, heat-treated cake mix to a gallon-sized zip lock bag or large mixing bowl. Add the powdered sugar and sprinkles.
1 cup (120g) powdered sugar, ¼ cup rainbow sprinkles
Seal the bag and shake to combine, or whisk to combine if using a bowl.
Pour the Chex cereal into a large mixing bowl.
8 cups Rice Chex cereal
In a microwave-safe container, melt the white candy coating in 20-30 second intervals until completely smooth and melted throughout.
16 ounces white candy coating
Pour the white candy coating over the cereal and gently toss to coat.
Spoon the candy-coated cereal into the zip lock bag or mixing bowl containing the cake mix/sprinkle mixture.
Seal the bag and shake well to coat the cereal, or gently toss to coat the cereal in the cake mix/sprinkle mixture all over, and serve.