Add the cooled sweet potato puree to the dry ingredients. Use your hand mixer or a sturdy whisk to beat them together. Then, add the room-temperature eggs, one at a time, beating well after each addition. The mixture will be thick and glossy. Now, slowly pour in the room-temperature buttermilk and the melted, cooled butter, whisking constantly. Finally, mix in the vanilla extract. At this stage, the filling will be a beautiful, creamy orange-brown color and will have the consistency of a thick cake batter. Resist the temptation to overmix once everything is incorporated.
Remove your chilled pie crust from the fridge. Pour the filling into the crust—it should come right up to the edge. Carefully transfer the pie to the oven (I place it on a baking sheet in case of spills) and bake at 400°F for 10 minutes. Then, without opening the door, reduce the oven temperature to 350°F (175°C) and bake for an additional 40-50 minutes. You’ll know it’s done when the edges are puffed and set, the center has a slight, gentle jiggle (like Jell-O), and a knife inserted near the center comes out mostly clean. The top may crack slightly, which is normal and beautiful. The aroma in your kitchen will be heavenly.
Pro Tips for Best Results
I tested the sweet potato prep three ways: roasting, boiling, and microwaving. Roasting won by a landslide. The dry heat caramelizes the natural sugars, adding a depth of flavor that boiling or microwaving simply can’t achieve. That caramelized note is what sets this pie apart. Trust me, take the time to roast.
Here’s what I learned the hard way about the filling temperature: adding hot sweet potato puree to the eggs will cook them prematurely, creating little scrambled egg bits in your custard. Always, always let your puree cool to room temperature before mixing. Similarly, using cold buttermilk can cause the butter to seize. Room temp ingredients are the key to a velvety-smooth filling.
To prevent the crust edges from burning, use a pie shield or make one from aluminum foil. I place it on the pie after the first 20 minutes of baking at 350°F. This allows the crust to bake to a perfect golden-brown without getting too dark, while the center of the pie finishes setting.(See the next page below to continue…)