Gather all ingredients. Preheat the oven to 350 degrees F (175 degrees C).
Beat eggs in a large bowl with an electric mixer until frothy.
Add sugar, butter, and flour; beat until smooth.
Stir in buttermilk, lemon juice, vanilla, and nutmeg.
Pour into pie shell.
Bake in the preheated oven until center is firm, 40 to 60 minutes.
Remove from the oven and cool for 1 hour before serving.
