Mix cereal, popcorn, and peanuts in a large bowl. Pour into prepared pan. (If using cake pans, just pour half in each pan.)

Mix together brown sugar, butter, and corn syrup in a sauce pan. Bring to a boil over medium heat, stirring constantly. Boil, without stirring, for 5 minutes. Remove from heat, and stir in vanilla extract and baking soda. Pour evenly over the cereal mixture and then gently stir it up to try to coat it.

Don't worry if everything doesn't get covered though! Just do your best. You'll have more chances to stir later.

Bake for 45 minutes. Every 15 minutes though, you'll want to stir the mixture. (So, you will stir it three times during that 45 minutes.) Cool the mixture in the pan(s) completely. However, make sure to stir the mixture frequently as it cool to try to break the mixture apart.

When cooled, stir in the chocolate chips and the white chocolate pretzels. Store in an airtight container.