Crust: Mix flour and sugar. Add softened butter, and mix with your hands, then add egg yolks. You may need to add 1 spoon of water. The dough should stick together, it should not become homogeneous. Roll out the dough, put it in a tart form, and rest it in the refrigerator for 30 minutes.
Peel the apple, cut it into cubes, and spread them on the dough, sprinkle with cinnamon, sugar, and lemon zest (you can also use orange zest). Place the tart in the oven heated to 180°C and bake for 30 minutes.
In the meantime, prepare the meringue, whip the egg whites, when they become foamy, slowly add sugar and vanilla sugar, and continue whipping. When meringue becomes glossy, it's done.
After 30 minutes of baking remove the tart from the oven, spread meringue on top, and continue baking for 15 minutes. Serve warm.Bon Appetit!
