1. Preheat the oven to 210°C (thermostat 7).
2. Place your dough in an oven-safe dish and prick the bottom with a fork.
3. Then, place parchment paper on your dough and finally place another dish (smaller than the first one) on top of the paper and the dough (this allows the dough to bake blind without it puffing up or burning).
4. Pre-bake for 15 minutes in the oven.
5. Wash the lemons, grate the zest. Squeeze them, pour the juice into a measuring glass with Cointreau and water to obtain 40 cl.
6. Bring everything to a boil in a saucepan.
7. In a separate bowl, beat the egg yolks and sugar until the mixture whitens. Add the cornstarch and lemon zest. Pour a little hot liquid, mix well, then pour everything back into the saucepan. Thicken without stopping stirring with a wooden spoon over medium heat (the mixture should not boil).
8. Remove from heat, incorporate the butter, let cool.
9. Beat the egg whites until stiff peaks form, then add the sugar while continuing to beat. Remove the weight from the tart. Spread the lemon cream on top, then the meringue.
10. Finally, bake the tart for 20 minutes in the oven. If the meringue browns too quickly, reduce the thermostat to 5 (150°C).
11. Serve chilled; this tart can also be prepared the day before.
12. Enjoy your meal!