Preheat the Oven: Preheat your oven to 275°F (135°C). This low temperature will help to crisp the mixture without burning the sugar.
Prepare Baking Sheets: Line two large baking sheets with parchment paper or silicone baking mats.
Mix Sugar and Cinnamon: In a small bowl, combine the 1 1/4 cup of sugar and 3 tablespoons of cinnamon. Mix well and set aside.
Prepare the Chex and Pretzels: In a large mixing bowl, combine the Rice Chex cereal and pretzel sticks. (add the pecans here if you opt to include them in the dish)
Prepare the Butter Mixture: In a separate bowl, mix together the melted butter, brown sugar, and vanilla extract until well combined.
Combine: Gradually pour the butter mixture over the Chex and pretzel mixture, gently stirring to ensure that everything is well coated but be sure to do this gently so not to crush the Chex cereal too much.
Add the Sugar Mixture: Sprinkle the cinnamon-sugar mixture slowly over the coated Chex mixture, incorporating continuously (and gently) to evenly coat all pieces.
Bake: Spread the mixture evenly on the prepared baking sheets. Bake for about 45 minutes, stirring and rotating pans every 15 minutes to ensure even baking.
Cool: Remove the baking sheets from the oven and allow the Churro Chex Mix to cool completely on the sheets. The mixture will continue to crisp as it cools.
Store or Serve: Once cooled, you can serve the Churro Chex Mix immediately, or store it in an airtight container for later enjoyment.