Sweet potatoes may not be savory enough for some palettes, but that might make them useful in a dessert. Yam pie is a solid tradition dating back several generations in the southern part of the United States. It is a simple mixture of mashed sweet potatoes with sugar, flour, nutmeg, cinnamon, egg, milk and vanilla that is poured into a pie crust for baking. When finished, this pie is very close in appearance — and taste — to pumpkin pie, which is another iconic Thanksgiving staple.
According to Professor Joseph Holloway of California State University, yams were a familiar food for American slaves, both those en route and those already working in plantations throughout the south. Holloway argues that yam pie is likely to have originated with them. It was among the few meager ingredients listed on the average slave ship records, which included black-eyed peas, plantain, okra, bread, fish, rice and yams.
It does not take many ingredients to make yam pie. Many households are already possess the eggs, milk, sugar, salt, butter, cinnamon and vanilla needed for the filling. A standard pie dough can be whipped up with some flour, sugar and egg, or simply bought at the store. The dough, then the filling, goes into the pie tin. An hour after baking at 350°F (about 177°C), a lightly browned skin on the pie will indicate that it is time for the yam pie to start cooling.
The East Texas Yamboree, a festival that began in 1935 to promote the local cash crop, has held a yam pie competition each of its years in operation. In 2011, with the festival reaching carnival size and more than 100,000 annual visitors, the pie-contest committee offered up a ratio of ingredients for the perfect yam pie filling on its Web site. A pie with about 1.5 cups (about 300 g) of mashed sweet potatoes or yams gets a "heaping" teaspoon (about 2.67 g) of flour, 1 cup (about 240 ml) of milk or cream, 2 tablespoons (about 28.5 g) of butter or margarine, 1 cup (about 201 g) of sugar and the yolks of three eggs. Of course, the contest is won by those who know how to tinker lightly with the mixture, though the committee forbids major ingredients changes like adding raisins, coconut or nuts.
After cooling, yam pie is regularly slathered with whipped cream. Some use marshmallows or marshmallow cream instead. Yam pie a la mode, with vanilla ice cream, would not be an uncommon choice either.