Measure Rice Chex into a large bowl and set aside.
Put white chocolate chips and shortening into a microwave safe bowl.
Microwave for 1 minute, stir and then micowave for 30 seconds longer.
Add root beer flavored oil and stir well.
Pour mixture over the Rice Chex and gently stir to coat.
Put chocolate coated Rice Chex into a gallon sized ziptop plastic bag.
Add the powdered sugar, zip the top of the bag shut and shake until the cereal is coated.
Spread on a piece of waxed paper to cool.