Preheat the oven to 275ºF and line a rimmed sheet pan with parchment paper.
Add the Chex cereals, mixed nuts, pretzels, and the mix-ins of your choice into a very large bowl.
In a separate microwave-safe bowl, add the butter. Heat in 30-second intervals until completely melted.
Add the Worcestershire sauce, seasoned salt, buffalo ranch seasoning, and ranch dressing mix (if using) to the melted butter and stir well to combine.
Pour half of the melted butter mixture over the cereal and mixins, and toss well to coat. Add the remaining half of the butter mixture, and toss well until everything is evenly coated.
Spread the prepared Chex mix evenly over each sheet.
Bake in the preheated oven for 25-35 minutes, stirring every 10-15 minutes, until lightly browned and crisp.
Remove from the oven and allow to cool completely on the baking sheet.
Transfer to a bowl with a tight lid or an airtight container.
Notes
Storage: Buffalo Ranch Chex Mix should last 1-2 weeks in an airtight container at room temperature. Allow to cool completely before transferring to a container, as condensation from a warm snack mix will cause it to spoil quickly.Slow cooker: Cook on "low" for 3 hours, stirring every hour. Allow to cool completely in the crock pot (or transfer to baking sheets) before transferring to storage containers. Air fryer: Cook for 6-8 minutes in an air fryer that has been preheated to 300ºF. Shake the basket 1-2 times during cooking. Gluten free: Use gluten-free pretzels in place of the regular ones, and use a gluten-free mix-in (or add a little extra cereal and nuts). As for Chex, several varieties are gluten free, including the corn and rice versions. For gifting: Cool completely before transferring to jars for gifting. Keeps for 1-2 weeks.