Preheat your oven to 250°F and position an oven rack in the center.

In a large disposable aluminum pan or a deep roasting pan, combine the Wheat Chex, Corn Chex, Rice Chex, Cheerios, pretzels, and salted nuts, mixing them well.

In a medium-sized bowl, whisk together the melted butter, Worcestershire sauce, seasoned salt, garlic powder, onion powder, and dried thyme until well combined. Gradually pour the butter seasoning over the snack mix, stirring continuously to ensure each piece is coated. Continue mixing until the seasoning is evenly distributed throughout the snack mix.

Place the pan in the oven and bake for 1½ hours, stirring the mix every 30 minutes to promote even toasting. Once the mix is golden and fragrant, remove it from the oven and allow it to cool. Serve immediately or store in an airtight container at room temperature for up to two weeks.