Measure out your cereal into a very large mixing bowl. Make sure the bowl is big enough to allow for easy stirring without crushing the cereal pieces.

In a microwave-safe bowl, combine your chocolate chips, creamy peanut butter, and butter. Microwave on high for 30 seconds, then stir. Continue heating in 15-second intervals until the mixture is completely smooth and glossy.

Stir in the vanilla extract to the melted chocolate mixture.

Pour the chocolate mixture over the cereal. Using a large rubber spatula, gently fold the chocolate into the cereal until every piece is well coated. Be gentle here so you do not break the squares.

Place the powdered sugar into a large gallon-size plastic bag. Transfer the chocolate-coated cereal into the bag as well.

Seal the bag tightly, leaving some air inside for room to move. Shake the bag vigorously until all the cereal is white and coated with sugar.

Spread the mixture out onto a sheet of wax paper or a baking sheet to cool. While the chocolate is still slightly tacky, toss in your Valentine M&Ms and sprinkles so they stick to the clusters.