Sweet Potato-Buttermilk Pie

Ingredients

• 0.8 cup buttermilk 
• 3 large eggs separated
• 2 tablespoons flour all-purpose
• 0.5 teaspoon ground cinnamon 
• 0.5 teaspoon ground nutmeg freshly grated
• 0.5 teaspoon kosher salt 
• 2 tablespoons juice of lemon fresh
• 15 oz piecrusts refrigerated
• 0.5 cup sugar 
• 1.5 lb sweet potatoes 
• 4 tablespoons butter unsalted melted
• 6 servings toppings: whipped cream 

Equipment

• bowl
• oven
• whisk
• wire rack
• plastic wrap

Directions

1. Bake potatoes at 400 for 1 hour or until tender; cool 10 minutes. Increase oven temperature to 45
2. Fit piecrust into a 9-inch pie plate according to package directions; fold edges under, and crimp. Prick bottom and sides of piecrust with a fork.
3. Bake at 450 for 9 to 11 minutes or until lightly browned. Reduce oven temperature to 37
4. Cut potatoes in half lengthwise. Scoop out pulp into a medium bowl; mash until smooth. Stir in butter and next 4 ingredients until well combined.
5. Whisk egg yolks until thick and pale.
6. Add sugar, and whisk 1 1/2 minutes or until lemon-yellow color. Stir egg yolk mixture into sweet potato mixture until well blended.
7. Add flour, 1 tsp. at a time, stirring until blended after each addition.
8. Add buttermilk, and stir until combined.
9. Whisk egg whites in a bowl until soft peaks form. Gently fold into sweet potato mixture until blended. Spoon sweet potato mixture into piecrust.
10. Bake at 375 for 35 to 40 minutes or until center is set.
11. Let cool on a wire rack 1 1/2 hours or until completely cool.
12. Serve at room temperature, or cover with plastic wrap, and chill 8 hours.
13. Serve with desired toppings.