First, grab a large mixing bowl for your Chex cereal and set it aside. Prepare a clean surface or a baking sheet by lining it with parchment or wax paper – this is where your delicious snack will cool.
In a spacious gallon-size zip-top bag, combine the powdered sugar and the dry instant pistachio pudding mix. Seal the bag tightly and give it a good shake until these two ingredients are perfectly blended.
Carefully pour the almond extract into the same zip-top bag. Seal it once more and shake again to ensure that delightful almond flavor spreads evenly throughout the sugar mixture.
In a separate medium microwave-safe bowl, combine your white chocolate melting wafers and the pieces of butter. Microwave for 30 seconds, then remove and stir thoroughly. Continue microwaving in short 15-second bursts, stirring well after each interval, until the mixture is completely melted and beautifully smooth (white chocolate likes gentle heat!).
Promptly pour the warm, melted chocolate and butter mixture over the Chex cereal in your large mixing bowl. Gently but quickly stir with a spoon or spatula to coat all the cereal pieces evenly before the chocolate has a chance to harden.
Transfer the chocolate-coated cereal into the zip-top bag that contains your sugar and pudding mix. Seal the bag securely and shake vigorously until every single piece of cereal is wonderfully coated with the green, sweet sugar blend.
Spread your freshly coated pistachio crunch out onto the lined surface or baking sheet. Allow it to cool down completely, letting the coating set. Once firm, it's ready to serve and share your love!