Chocolate wafer cookies are very thin, crispy chocolate cookies that are commonly called for when making chocolate crumb crusts and icebox cakes. They have a bittersweet cocoa flavor to them and a very dark , nearly black, color. They’re an unusual cookie these days, although they have been around since the 1930s, because these are their two primary uses and you rarely see them in other applications. As a result, they can be difficult to find and not every grocery store will carry them.
The drawback to using these cookies in a recipe is that they tend to be fairly expensive for a small box of cookies, mostly because they’re not used for all that much. You will need them in some recipes – such as some icebox cakes that rely on their particular size and shape – but when it comes to chocolate crumb crusts, you will often be better off opting for different chocolate cookies to make a crust that ends up being less expensive to produce and just as tasty. Chocolate graham crackers are one option for chocolate crumb crusts, and Oreo wafer cookies (with the cream filling removed) can also be crushed into excellent chocolate crumbs.