Measure rice cereal into a large mixing bowl and set aside.

In a microwave-safe bowl, combine white chocolate chips, peanut butter, and butter.

Microwave the mixture on high for 60 seconds, then stir until smooth; heat in additional 15-second intervals if required to reach a fluid consistency.

Incorporate vanilla extract into the melted chocolate and peanut butter mixture.

Pour the liquid mixture over the rice cereal and fold gently with a spatula until every piece is evenly coated.

Transfer the coated cereal into a large 2-gallon resealable plastic bag.

Add the powdered sugar to the bag, seal tightly, and shake vigorously until the cereal is uniformly whitened.

Spread the mixture onto a parchment-lined baking sheet and allow to cool completely at room temperature for 20 minutes.

Toss the cooled mixture with pastel chocolate candies, malt balls, and sprinkles.

Store in an airtight container to maintain crispness.