Preheat oven to 250F and line 2 baking sheets with parchment paper
Pour rice chex, wheat chex, cheez its, pretzels and roasted peanuts into a large mixing bowl and mix them together.
Place a small sauce pan on the stove over low heat and place the stick of butter and brown sugar in the pan. Allow the butter to melt completely, then mix the sugar into the butter.
Whisk in the worcestershire sauce and increase the heat just a little to medium-low. The mixture should start to lightly simmer. Allow the mixture to simmer for 3 minutes - mixing constantly. Then, remove from the heat.
While it is still hot, pour the liquid over the dry ingredients in the mixing bowl and toss to coat thoroughly.
Pour everything onto the two lined baking sheets and spread the ingredients out to create an even layer.
Sprinkle flakey sea salt over the top and place in the oven at 250F for 40 minutes, tossing once halfway through.
Remove from oven and allow to cool completely before serving or storing for later. Store in an airtight container at room temperature for up to 5 days.
Notes
If you don't want to use cheez its, you can replace them with goldfish crackers or oyster crackers.
Swap the peanuts for roasted cashews or pecans or omit the nuts completely.
Watch and stir the sugar mixture the entire time that it is cooking.It can very easily bubble up too much and boil over. Keep the heat low enough so that it is just at a light simmer and not a boil.
Toss the sugar mixture into the dry ingredients thoroughly. For the best taste and texture you want all of the dry ingredients to be evenly coated in the butter and sugar sauce. This requires mixing as evenly as possible while the sauce is still warm.
Spread the mixture onto 2 baking sheet or bake in 2 batches. If you pour the entire batch onto one baking sheet, you will get large clumps that will be soggy in the middle instead of crispy.