I'm surprised that there's no leavening included in this recipe. Is this an error?

An icebox cake is traditionally made with wafer cookies and whipped cream. The cookies absorb moisture from the whipped cream and soften during refrigeration. I assume the "cake" layers in this recipe are meant to come out thin and flat like wafers rather than light like a cake.

I don't believe it is -- the recipe was based off this Martha Stewart ice cream sandwich cookie, which also has no leavener: http://www.marthastewart.com/315819/classic-ice-cream-sandwiches