American dessert recipes are incredibly diverse thanks to a massive influx of immigrants in the past. Rustic and generous is how I would describe their after-meals.
The noticeable influence of different cultures is well-known.
As a result of this immigration stream, the expansion, and change have continued throughout the centuries. The general cuisine would reflect this wide diversity.
This mixing and matching of many different styles make theirs unique.
Some American dessert recipes are typically from the South, others from New York, the Mid-West, or wherever the dessert got its roots and/or popularized. But only a true American would know where their popular dessert comes from.