It is usually made as a large tart in an open pie shell without a top crust. The filling consists of mashed sweet potatoes, milk, sugar and eggs, flavored with spices such as nutmeg. Other possible ingredients include vanilla or banana extracts. The baked custard filling may vary from a light and silky to dense, depending on the recipe's ratio of mashed potato, milk and eggs.
Though creamy vegetable pie recipes date back to Medieval Europe, sweet potato pie appears in the southern United States from the early colonial days. Like many sweet potato recipes, sweet potato pie was likely developed by African-American slaves from traditional African cuisine, making it a staple of soul food today. Recipes for sweet potato pie first appeared in printed cookbooks in the 18th century, where it was included with savory vegetable dishes. By the 19th century, sweet potato pie was more commonly classified as a dessert.