In a large mixing bowl, combine the Rice Chex, Corn Chex, pretzel twists, and peanuts. Gently toss until evenly mixed.
In a microwave-safe bowl, add the chocolate chips, peanut butter, honey (or maple syrup), vanilla extract, and sea salt. Microwave in 30-second intervals, stirring in between, until the mixture is smooth and fully melted.
Pour the melted chocolate mixture over the Chex, pretzels, and peanuts. Use a spatula to carefully fold and coat the dry ingredients thoroughly, ensuring every piece is covered.
Spread the coated Chex mix onto a large baking sheet lined with parchment paper in an even layer. Allow it to cool completely at room temperature for about 30-45 minutes, or pop it in the fridge for quicker setting.
If desired, fold in M&M's (or other candies) once the mix has cooled and set.
Once set, break the Chex mix into pieces and store in an airtight container or serve immediately!