Milano cookies are a trademarked cookie manufactured by Pepperidge Farm as part of their series of "European" cookies. Each cookie consists of a thin layer of chocolate sandwiched between two biscuit cookies.
The Milano was created as a result of Pepperidge Farm's original cookie concept, the Naples, which was a single vanilla wafer cookie with dark chocolate filling topping it. The problem this posed was that Naples cookies would end up stuck together when shipped to and sold in warmer climates. The company resolved the problem by sandwiching Naples cookies together, creating the new Milano variety.
The original variety used a filling of dark chocolate. Many additional varieties have since been marketed, such as milk chocolate and double chocolate; other flavors include a layer of mint or sweet orange paste in addition to some form of chocolate.
In Canada, they are sold under the brand name "Monaco" rather than "Milano," because the name Milano was already in use in Canada prior to Pepperidge Farm's arrival in the market.