Knead shortcrust pastry out of the dough ingredients and line a tart pan with it (not too thin). Pierce (possibly put peas on top for blind baking) and bake for 20 minutes at 200 degrees. The dough should be light brown on the edge.
Squeeze the lemons and rub the peel of two lemons.
Put the eggs, sugar and lemon juice in a bowl and beat over a double boiler for about 10 minutes until the water simmers and the mixture is creamy and firm. Stir in butter and lemon zest. Fill the finished base with the lemon curd. Let cool down.
If you want, you can decorate the cake with cream.