Preheat oven to 350°F.
Line a 9-inch pie plate with unbaked pie dough.
In a medium bowl, whisk the eggs until foamy. Beat in butter, sugar, and flour until fluffy.
Add the buttermilk, vanilla extract, lemon juice, and nutmeg, along with a small pinch of salt, and mix until smooth.
Pour the batter into the prepared crust and bake for 45-55 minutes until a knife inserted in the center comes out clean.
Cool completely before serving.
