1. Crush 18 Oreo cookies into fine crumbs using a food processor or zip-top bag and rolling pin. Reserve a few larger chunks for topping if desired. Mix cookie crumbs with 1 1/2 cups powdered sugar in a large bowl. Set aside.

2. In a microwave-safe bowl, combine 1 1/4 cups white chocolate chips and 3 tablespoons butter. Microwave in 20-second intervals, stirring after each, until melted and smooth (about 60 seconds). Stir in 1 teaspoon vanilla extract.

3. Place 6 cups Rice Chex cereal in a large mixing bowl. Pour the melted white chocolate mixture over the cereal. Gently fold until all pieces are evenly coated.

4. Add the coated cereal to the bowl with the Oreo-powdered sugar mixture. Toss gently until each piece is well covered. Top with reserved Oreo chunks if desired.

5. Spread puppy chow on a baking sheet to cool and set. Transfer to a serving bowl or airtight container. Enjoy immediately or store for up to 5 days.