"Pessimism is as American as apple pie - frozen apple pie with a slice of processed cheese"

This quote by George Will is a funny way of stating that pessimism is a part of the American culture. He is suggesting that pessimism is as much a part of the American identity as apple pie, which is a classic American dessert. By including the expression "frozen apple pie with a piece of processed cheese," Will is stressing the concept that pessimism is a part of the American culture, but it is not always a favorable thing. The phrase "frozen apple pie with a piece of processed cheese" implies that pessimism is a low-cost, synthetic variation of the real thing. To put it simply, pessimism is a part of the American culture, however it is not necessarily a good idea. Will is recommending that pessimism belongs of the American identity, but it ought to not be welcomed or celebrated.