Preheat the oven to 180°C (356°F).
Mix almond flour, butter, and erythritol to make the tart dough.
Let the dough rest in the refrigerator for 20 minutes.
Evenly spread the dough in the tart mold.
Combine the egg filling (egg, milk, vanilla extract, erythritol) thoroughly.
Pour the egg filling over the dough.
Bake in the oven at 180°C (356°F) for 20–25 minutes.
Let cool and remove from the mold.