Heat oven to 250F.

Mix cereal and pecans in a 9x13 pan and set aside.

In a microwave-safe bowl, combine corn syrup, brown sugar, and butter.

Microwave on high for 30-second increments, stirring in between until the mixture is boiling.

Stir vanilla and baking soda into the butter mixture until combined.

Pour wet ingredients into the cereal mixture and stir until evenly coated.

Bake for 1 hour, stirring every 20 minutes.

Spread the mixture evenly on waxed paper to cool, breaking apart as needed for bite-size pieces.