1 1/2 pounds sweet potatoes about 2 medium potatoes
4 tablespoons unsalted butter
2 tablespoons fresh lemon juice optional
1/2 teaspoon nutmeg freshly grated
1/2 teaspoon ground cinnamon
1/2 teaspoon kosher salt
3 large eggs, separated
1/2 cup sugar
2 tablespoons all-purpose flour
3/4 cup buttermilk full- or low- fat or make your own
1 All-Butter, Really Flaky Pie Crust prebaked
Whipped cream for serving
Equipment
oven
3-quart stock pot with strainer
large bowl
fork or potato masher
wooden spoon or rubber spatula
small bowl
whisk or electric hand mixer
pie dish
Directions
Preheat the oven to 375°F.
Pour 1 1/2 inches of water into a 3-quart stock part with a strainer basket suspended over it and bring to a boil over medium-high heat. Add the sweet potatoes, cover and steam until fork-tender, about 20 minutes.
Place the steamed sweet potatoes in a large bowl and let cool to room temperature. Mash them into a smooth puree with a fork or potato masher.
Add the butter, lemon juice if using, nutmeg, cinnamon, and salt and mix thoroughly with a wooden spoon or rubber spatula after each addition.
In a small bowl, beat the egg yolks lightly with a whisk, about 30 seconds. Add the sugar and beat until they're a creamy lemon-yellow color, about 1 1/2 minutes.
Add the egg mixture to the sweet potato mixture and stir until the eggs are thoroughly incorporated and the filling is a consistent bright orange color.
Add the flour a little at a time, stirring after each addition until thoroughly incorporated. Add the buttermilk and again stir until smooth and even.
With a cleaned whisk, or electric hand mixer, whisk the egg whites to soft peaks in a clean, dry bowl.
With a wooden spoon or rubber spatula, gently fold the egg whites into the sweet potato-buttermilk mixture until thoroughly combined.
Pour the mixture into the prebaked crust and bake on the middle rack of the oven until the center is firm and set, 35 to 40 minutes.
Remove the pie from the oven and cool completely on a rack. Serve at room temperature with a dollop of whipped cream.