This week, Kroger had the Pepperidge Farm Creme 3-Layer Cakes on sale for $2.
This beast is rated at 1680 calories (1680 kcal) for the 19 oz package.
The most used ingredient is...sugar.

Refer to the attached Nutrition Facts snapshot.
Modification:
I've found that with a simple mod of skimming the icings, you can maybe save 600+ kcal from the package. The attached picture shows the packed volume of the icings compared to bare cake. Yes, it's almost 1/4 the size of the cake. That's a lot of sugar.
It tastes a lot better without all the icings and the guilty calories.