Place the cereal in a large bowl.
In the microwave or on the stovetop, melt the chocolate and peanut butter.
If using the microwave: microwave in a bowl, in 30-second intervals, stirring between each, until nearly completely melted; stir to melt completely.
If using the stovetop: in a small saucepan, over low heat, stir until chocolate is melted.
Once the chocolate is melted, stir in the vanilla.
Pour the chocolate-peanut butter mixture over the cereal and stir vigorously to coat.
Refrigerate until the chocolate is cool, tacky and less shiny than melted chocolate; 10 to 15 minutes.
Remove from the refrigerator and spread the cereal, in an even layer, on a sheet pan.
With a spoon or fine-mesh sieve, sprinkle some of the powdered sugar evenly over the cereal; add a pinch of salt; toss with a spoon or your hands, or both, until evenly coated.
Repeat with the remaining powdered sugar; adding the sugar in batches ensures it doesn’t all soak into the chocolate; set aside to set, at least 5 minutes.
Store in an airtight container, at room temperature, for 3 to 4 days, or in the refrigerator or freezer for months.
