Step 1: Grate the zest from the lemon.
Step 2: Mix lemon zest, egg, egg yolk, sugar and salt in a bowl for the pastry.
Step 3: Beat the mixture. Incorporate slowly the butter, then the flour.
Work the pastry with your hands. Roll it into a ball and rest in a fridge for at least one hour.
Combine the milk and the vanilla in a saucepan and bring to a boil. Remove the bean.
Step 6: Beat the sugar and egg yolks. Stir in the flour and the rum. Add slowly the hot milk. Bring the cream back into the saucepan and cook over very low heat. Stir the mixture. Remove from the heat when the cream begins to boil. Put the butter. Let the cream cool.
Step 7: Preheat the oven at 380 F (200 C).
Step 8: Butter a round cake pan. Roll out two third of the pastry. Line the bottom and sides. Fill with the cream. Cover with the remaining pastry.
Step 9: Beat an egg. Brush it the top of the cake.
Step 10: Bake in the oven for 45 minutes.
Wine suggestion: Sweet white wine such as Jurançon (French