Sweet potato is the main ingredient in classic Southern sweet potato pie.
The filling is typically made by mashing cooked sweet potatoes with sugar, eggs, milk or evaporated milk, butter, and spices such as cinnamon or nutmeg. It is baked in a pastry crust until set.
Sweet potato pie became especially associated with African American and Southern holiday cooking. Sweet potatoes were widely cultivated in the South and could be stored for long periods, making them practical for both everyday meals and celebrations.
In American usage, sweet potatoes are sometimes casually called yams, but the plants are different. Commercial “candied yams” may use sweet potatoes, while sweet potato pie is conventionally named for the ingredient used in its filling.