1: Prepare the creamy custard by combining milk, cornstarch, vanilla, and egg yolk in a saucepan.
2: Add the whole lemon peel and cook until thickened.
3: In a separate bowl, mix almond flour, butter, and a pinch of salt to create the base.
4: Add the healthy custard into the almond base mixture.
5: Squeeze in the lemon juice and mix with the sugar substitute.
6: Pour the mixture into the prepared pie crust.
7: Add more custard on top and sprinkle with grated lemon peel.
8: Chill before serving.
