A Thanksgiving favorite, sweet potatoes are most commonly baked into a casserole for the holiday dinner table. But they can be taken up a notch to dessert status by being transformed into a delightful, custardy pie. They are actually a rather unique food in terms of pie fillings as they are one of the only vegetables regularly made into sweet pies (rhubarb is another; pumpkins and other squash are technically fruit). 
 
But in the 19th century, white potatoes were also a common pie filling. Philadelphia Quakers liked to make “Quarterly Meeting Pie,” a popular dessert served at their Quarterly Meeting dinners, which was actually a baked (white) potato pudding. Philadelphia pastry chef and cooking school instructor Mrs. Goodfellow referred to it as White Potato Pie. In this version, the potatoes are grated instead of mashed, then mixed with butter, sugar, eggs, brandy and flavorings. Another Goodfellow recipe for potato pudding calls for boiling the potatoes and then sifting them through a colander before mixing with the other ingredients to make the custardy pies. 
 
Mrs. Goodfellow’s recipes for sweet potato pie and pudding are almost identical, intimating that the tubers were probably used interchangeably depending on what was readily available. 
 
Her two recipes:
 
SWEET POTATO PIE.
Boil the potatoes and peel them; rub through a colander, and to every pint of potatoes take a cupful of rich cream, 4 eggs beaten separately. Cream a cup of butter and one of sugar together, add the yolks to the sugar and butter, and beat well. Then stir in the potatoes and beat again. Season with grated nutmeg and a wine glass of brandy. Gently stir in the beaten whites of the eggs. Line deep pie plates with puff paste, and fill with this mixture. Put into the range and bake. This must have no top crust. (Source: ‪Colonial Receipt Book: Celebrated Old Receipts Used a Century Ago by Mrs. Goodfellow's Cooking School)
 
SWEET POTATO PUDDING.
Contributed by Mrs. John H. Easby, Philadelphia, Pa.
Grate 3 or 4 good sized raw sweet potatoes. Lay some slices of good butter in a dish, on this sprinkle some of the grated potatoes, about one half. Grate in the potatoes a nutmeg and a very little cinnamon, and scatter over 2 large spoonfuls of brown sugar, then the rest of the potatoes, more butter and sugar and mix 1 wineglass of rosewater and a cup of cream together and 1 wineglass of wine and brandy mixed. Stir all these ingredients well together. Bake very slowly 2 hours and serve hot as a dessert. (Source: Famous old receipts: used a hundred years and more in the kitchens of the North and South, compiled by Jacqueline Harrison Smith)
 
The version I made is adapted from both recipes, and it is absolutely delicious. It has a fluffy, almost mousse-like texture as a result of beating the eggs separately, just as Mrs. Goodfellow used to do in order to make her products light and airy. I used another Goodfellow trick mentioned in these recipes – the addition of brandy. Back then liquor or wine was often added to a recipe to help preserve it from going bad in the days before refrigeration. It also adds flavor, but feel free to omit it if you’d like. Unlike her, I had the benefit of my modern-day food processor and stand mixer to make this recipe super easy. 

Sweet Potato Pie

• 1 ½ pounds sweet potatoes
• 3 large eggs, separated
• 2/3 cups sugar
• 1 tsp cinnamon
• ½ tsp freshly grated nutmeg 
• ½ cup milk
• 2 tbsp brandy 

1. Make and prebake your favorite pie crust. Place on a wire rack to cool. 
2. Boil the sweet potatoes until tender, about 30-40 minutes. Let cool and then scoop out the flesh into a large bowl and mash it up a bit.
3. Transfer to the large work bowl of a food processor. Add the egg yolks and remaining ingredients and process until smooth. 
4. Beat the egg whites until soft peaks form and then add to the other ingredients and process again until well incorporated.
5. Scoop into the prebaked pie shell and bake at 350F for 1 hour or until set. 
6. Cool on wire rack. 

Yield: One 9-inch pie, 8-10 servings