In a mixing bowl, combine flour and sugar. Cut in butter until mixture resembles coarse crumbs. Add egg yolk and cold water, mix until dough forms. Press into tart pan.
Bake crust for 15 minutes. Let cool.
In another bowl, whisk together sugar, eggs, lemon zest, lemon juice, and heavy cream. Pour into cooled crust.
Bake for 20-25 minutes, until filling is set. Let cool.