I have eaten plenty of oatmeal cookies over the years but never oatmeal cake. I wonder if there is much of a difference. The ingredients all sound about the same between the two; white and brown sugar, cinnamon and nutmeg. Maybe this is basically a recipe for one big oatmeal cookie!
As a side note the second ingredient listed is a stick of Oleo, which is what margarine used to be called. You can find more information about Oleo here.