In a mixing bowl, combine flour and sugar. Add cold butter and mix until crumbly. Add egg yolk and cold water, mix until dough forms. Press dough into tartlet pans.
Bake tartlet shells for 10-12 minutes or until golden. Let cool.
In another bowl, whisk together lemon juice, lemon zest, sugar, eggs, and heavy cream until smooth. Pour filling into cooled tartlet shells.
Bake for 15 minutes or until filling is set. Let cool before serving.