Heat oven to 275°F. Line two baking sheets with parchment paper or silicone baking mats. Mix together your choice of 8 cups mixed bite-sized snacks in a large bowl.
Mix together ¼ cup unsalted butter, ¼ cup packed brown sugar, 2 Tablespoons soy sauce, 1-2 Tablespoons Sichuan chile flakes, 1 teaspoon five spice powder, ½ teaspoon Sichuan peppercorn, ½ teaspoon garlic powder, and ½ teaspoon MSG in a small saucepan over medium heat. Cook, stirring often until butter is melted and the ingredients are uniformly mixed, about 3-5 minutes. Pour the seasoning mixture over the snack mix and stir gently until evenly coated.
Divide the mixture between the two prepared baking sheets and spread evenly. Bake until the mixture is dry, about 1 hour, stirring every 15 minutes. Let the mixture cool completely (the coating will become crunchy as it cools) and store in an airtight container at room temperature for up to a month.
Notes
Choose neutral-flavored bite-sized snacks like cereal (Chex, Shreddies, Cheerios, etc.), small rice crackers, pretzels, nuts, or crackers. You can also use gluten-free snacks (rice or corn chex, gluten-free cheerios, rice crackers, etc.) to make your snack mix gluten-free.I used 2 Tablespoons of coarse gochugaru, which is milder than Sichuan chile flakes. You could also use regular red pepper flakes, which are spicier than both. If you use either Sichuan chile flakes or red pepper flakes, I recommend reducing the amount to 1 Tablespoon, or perhaps less if you don't want your snack mix to be too spicy.