I looked at several peanut butter chex mix recipes and they all seemed to have ingredients I wanted to avoid, or took more time than I wanted to take, so I made my own, insanely easy version. Sometimes "simple" is just better.
1 box Chocolate Chex cereal
2 bags of Reece's Peanut Butter Chips
1 bag of Peanut Butter M&M's
1/2 - 1 bag of milk chocolate chips
salt
Melt 3/4 of the peanut butter chips in a very large bowl. You might need to do this in 2 batches.
Dump everything else into the bowl, including the rest of the peanut butter chips.
Stir until everything is coated.
I love it this way but you can also mix in different things like: colored sprinkles, pretzels, Reece's Pieces, crushed oreo, etc...
Once coated, spread the mixture out on a large sheet pan or two so that it can harden a bit.
Sprinkle with a little kosher salt and let it rest until set.
