Divide Chex cereal into two large bowls (2 ½ cups in each).

Place 1 cup powdered icing sugar in a gallon-sized ziptop bag and set aside.

Scrape Oreo filling out of cookies and save for later in the recipe.

Pulse Oreo cookies in a food processor until fine crumbs remain.

Dump the Oreo crumbs in a second gallon-sized bag and add ½ cup powdered sugar. Seal and shake to combine.

Melt the white chocolate chips in a small microwave-safe bowl and melt for 25 seconds. Stir and reheat as needed. Add Oreo filling from step 3 to the melted white chocolate and stir until completely combined.

Pour white chocolate mixture over the first bowl of the Chex cereal and stir to coat.

Scoop the Chex cereal into the bag with the (plain) powdered icing sugar, then seal and shake to coat the cereal completely with the powdered icing sugar.

Heat the chocolate chips in a small microwave-safe bowl and melt for 25 seconds. Stir and reheat as needed.

Pour melted chocolate chips over the second bowl of Chex cereal and stir to coat.

Scoop the Chex cereal into the bag with the Oreo crumb and powdered sugar mixture, then seal and shake to coat the cereal completely.

Spread the two candy and powdered sugar-coated cereal mixtures onto a cookie sheet in a single layer and allow the chocolate to set completely for approximately 30 minutes.

Stir the two cereal mixtures together before storing or serving. Optionally, garnish with mini OREO cookies.