In a mixing bowl, combine flour, sugar, and salt. Add the cold butter and mix until the mixture resembles coarse crumbs. Add the egg yolk and mix until the dough comes together.
Press the dough into a tart pan. Prick the bottom with a fork and bake for 15 minutes or until golden brown. Let it cool.
In another bowl, whisk together sugar, eggs, lemon juice, lemon zest, heavy cream, and dried lavender until smooth.
Pour the filling into the cooled crust. Bake for 20-25 minutes or until the filling is set. Let it cool before serving.