Set up the cereal in an oversized mixing bowl or a clean brown paper bag reinforced with a second bag. Leave enough room to lift and turn the squares without compressing them.

Combine the condensed milk, melted butter, and chips in a large microwave-safe bowl, then heat in 30-second rounds with thorough stirring after each round until the chips melt. The mixture is ready when stirring leaves it smooth and evenly blended, with no solid chip centers.

Stir the dry pudding mix into the melted mixture, then blend in the vanilla and salt. Look for an even pastel-green color with no streaks or dry powder pockets.

Distribute the green coating over the cereal, fold gently to cover the squares, then add the powdered sugar and toss again. The finished pieces should have a powdery exterior rather than large patches of exposed sticky coating.

Leave the coated cereal uncovered until cool, then transfer it to an airtight container. A cooled piece should feel dry on the outside rather than warm and tacky.