Prep. To prepare the oven for baking, preheat it to 250 degrees. Then, take a large-rimmed baking sheet, cover it with foil, and give it a light coating of cooking spray. This will ensure that the Churro Chex Mix bakes evenly and doesn't stick to the pan.
Mix the cereal and pretzels. Combine rice cereal, corn cereal, and pretzels in a plastic bag. Shake the mixture together and once mixed, divide the mixture evenly into two large mixing bowls.
Cook the caramel coating. In a medium saucepan over medium heat, melt butter, 1/2 cup of the sugar, brown sugar, and honey until the mixture becomes smooth and creamy. Once the edges of the saucepan start to bubble, continue cooking and stirring for 1 minute. Then, incorporate the baking soda into the mixture and give it a good stir.
Coat the cereal mixture. Divide the prepared mixture in half and pour one portion into one of the cereal mix bowls. Toss the ingredients together until they are evenly coated. Repeat the same process with the remaining portion of the mixture, pouring it into the other cereal mix bowl and tossing it to coat the ingredients thoroughly.
Mix the topping. In a small bowl whisk together the remaining 1 teaspoon of cinnamon and 1/4 cup of sugar.
Add the remaining cinnamon sugar mixture. Spread the prepared mixtures evenly onto the prepared sheet pans, making sure to distribute them in a single layer. Sprinkle the mixture with some additional cinnamon and sugar, then use your hands to toss and coat the cereal thoroughly.
Bake. Place the mixture into the oven to bake for 10 to 15 minutes. Remove and toss the ingredients to coat them and spread them in a single layer once again. Return the sheet pan to the oven to cook for an additional 10 to 15 minutes.