In a large zip top baggie, combine cake mix and powdered sugar. Seal bag and shake to evenly combine ingredients.
In a large glass bowl, combine white chocolate and shortening. Melt according to directions on package. I heated mine in the microwave for 30 seconds then stirred, another 30 seconds and stirred again, then continued heating in 10 second intervals and stirring until completely melted.
Pour white chocolate over cereal and mix carefully using a spatula.
Empty the coated cereal into the baggie with the cake mix and powdered sugar and shake gently until all cereal is evenly dusted. Top with carrot cake sprinkles if desired.