Roast the sweet potatoes for about 45 minutes until soft, then let cool and peel.
Melt 3/4 cup of unsalted butter in a saucepan over medium heat until browned, about 5-7 minutes.
In a mixing bowl, combine mashed sweet potatoes, 1/4 cup browned butter, brown sugar, cinnamon, nutmeg, ginger, rum (if using), eggs, vanilla, and heavy cream until smooth.
Roll out the first pie crust and fit it into a 9-inch pie dish. Blind bake at 350°F (175°C) for 10 minutes, then allow to cool.
Spread the sweet potato mixture evenly in the crust.
In a separate bowl, whisk together the remaining browned butter, eggs, granulated sugar, flour, buttermilk, lemon juice, lemon zest, vanilla, salt, and nutmeg. Pour over the sweet potato layer.
Cover with the second pie crust, trim excess, crimp edges, brush with beaten egg, and sprinkle with turbinado sugar.
Bake at 350°F (175°C) for 55-65 minutes until the top is golden brown and the filling is set.
Let cool for at least 2 hours before slicing. Serve with whipped cream.
Send me this recipe!
Just enter your email below and get it sent straight to your inbox!
Notes
Store leftovers in the refrigerator for up to a week or freeze for up to three months.