Preheat oven to 350 degrees.

If using purchased pie crust (such as Pillsbury), line 9” pie plate with crust and crimp edges. Set aside.

In a large bowl combine the lemon zest and juice, granulated sugar, the egg yolks, softened butter, milk, and flour. Mix with a hand mixer until combined.

In a separate bowl, with a hand mixer, beat the egg whites until stiff peaks form.

Fold the egg whites into the lemon mixture until combined.

Pour filling into the unbaked pie shell.

Bake pie until crust is golden and top of pie is brown, approximately 45 minutes to one hour. The top of the pie will look like a sponge, with a creamy filling underneath.