In a large bowl, melt the white chocolate chips in the microwave in 15 second increments, stirring in between each. Repeat until the white chocolate is completely melted.
In a separate large bowl, melt the semi-sweet chocolate.
Take two gallon size plastic bags and pour the white chocolate into one and the semi-sweet chocolate into the other.
Add 3 cups of Chex cereal to each one and close the bags, leaving as much air in them as possible. Vigorously shake to coat.
Add 1 cup powdered sugar and 1/4 teaspoon of salt to each bag, close and vigorously shake to coat.
Pour the two different Chex cereals into a large bowl and add the chopped Oreo cookies. Use your hands or two large spoons to mix together.
Enjoy!
Notes
To store: Keep in a sealed plastic bag for up to 2 weeks.