Prepare the pastry according to the basic recipe. Butter the mould (24 cm wide) lay the pastry leaving a border, cover with baking foil and beans and bake at 180°C for about 20 minutes. In the meantime, prepare the lemon curd.
Wash the lemons and grate the skin of 2 of the 3 fruits, squeeze all the fruits and pour the juice in a pan with the grated skin, sugar and corn starch. Heat it slowly and blend it with a wooden spoon until warm. With a fork gently beat the eggs and pour slowly into the juice always mixing with the wooden spoon until the mixture becomes thicker. You can see it on the spoon if the time is over. Take the pan away from the fire, add the butter and melt it. Leave the curd to cool down at room temperature stirring it from time to time.
When both the pastry and curd are lukewarm, pour the curd on the pastry and leave it to cool down for a couple of hours before serving.