Preheat oven: Set your oven to 250°F (120°C). Line a large rimmed baking sheet with parchment paper to prevent sticking and make cleanup a breeze.
Combine dry ingredients: In a large mixing bowl, add the Crispix cereal and pecan halves. Gently toss them together so the nuts are evenly distributed without crushing the cereal.
Make the caramel sauce: In a small saucepan over medium heat, melt the butter. Stir in the brown sugar and light corn syrup. Continue stirring constantly as the mixture comes to a gentle boil. Let it boil for 2 minutes to fully dissolve the sugar and thicken the syrup slightly.
Add vanilla and baking soda: Remove the saucepan from the heat and immediately stir in the vanilla extract and baking soda. The mixture will foam and expand—this is normal and gives the caramel a light, crisp texture once baked.
Coat the mix: Quickly pour the hot caramel mixture over the cereal and pecans in the bowl. Use a heat-safe spatula to toss and stir until everything is evenly coated. Work quickly before the caramel starts to set.
Spread and bake: Transfer the coated mixture onto the prepared baking sheet. Spread it out into an even layer to allow even baking. Bake for 1 hour, stirring gently every 15 minutes to ensure consistent caramelization and prevent clumps.
Cool completely: Remove the tray from the oven and let the mixture cool on the baking sheet. As it cools, it will crisp up into that signature crunchy texture. Once fully cooled, break into bite-size pieces.
