In a large mixing bowl, pour in your 8 cups of Chex cereal. Set aside while you prepare the chocolate mixture.
In a microwave-safe bowl, combine 1 ½ cups of semisweet chocolate chips, ¾ cup of creamy peanut butter, and 4 tablespoons of salted butter. Microwave the mixture in 30-second intervals, stirring after each interval, until everything is melted and smooth.
Once your chocolate mixture is melted, stir in 1 teaspoon of vanilla extract.
Pour the melted chocolate mixture over the Chex cereal and gently fold with a spatula or wooden spoon.
Transfer the chocolate-coated cereal into a large zip-top bag. Add 2 cups of powdered sugar, seal the bag, and shake vigorously until all the pieces are coated.
Spread the Muddy Buddies onto a large baking sheet or platter to cool. Once cool, enjoy immediately or store for later!