In a large microwave-safe bowl, combine white chocolate chips and coconut oil. Microwave on high for 20-30 seconds, then stir. Repeat until smooth.

Add rice Chex to the melted white chocolate mixture, stir gently to coat. Transfer to a Ziploc bag with powdered sugar, seal, and shake until covered.

In the same bowl, melt semisweet chocolate chips with remaining coconut oil as before. Stir until smooth.

Fold remaining rice Chex into the melted chocolate and transfer to another Ziploc bag with powdered sugar, seal, and shake until coated.

Combine both batches of Chex in a large mixing bowl. Lightly crush Oreos and fold gently into the mix.

Store the puppy chow in an airtight container. It can be kept at room temperature for up to a week.