Beat sweet potatoes, eggnog, eggs, sugar, butter, rum, cinnamon, and nutmeg together in a bowl with an electric mixer until smooth.
Pour sweet potato mixture into prepared pie crust.
Bake pie in the preheated oven for 10 minutes. Reduce heat to 300 degrees F (150 degrees C) and continue baking until pie is set, 50 to 55 minutes. Chill in the refrigerator for at least 2 hours or overnight.