In a large bowl, whisk the flour, sugar, salt, and lemon zest together.

Add the cold cubed butter and rub it into the flour with your fingertips until the mixture looks like coarse sand.

Add the egg yolks and whole egg. Mix with a fork, then bring the dough together with your hands until it just holds. Don't knead it or the crust turns tough.

Shape into two disks, one about two-thirds of the dough and one-third for the lattice. Wrap both in plastic and chill for 30 minutes.

While the dough chills, drain the ricotta in a fine-mesh sieve for 30 minutes if it looks wet.

Whisk the ricotta, sugar, whole eggs, lemon zest, vanilla, Sambuca (if using), and salt together in a bowl until smooth and no lumps remain.

Heat the oven to 170 C / 340 F. Roll the larger disk of dough on a floured surface to about 3 mm thick and line a 26 cm / 10-inch tart pan with a removable bottom. Trim the edges and prick the base a few times with a fork.

Pour the ricotta filling into the shell and smooth the top with a spatula.

Roll the remaining dough and cut into strips about 1.5 cm / 0.6-inch wide. Weave into a lattice over the filling, pressing the ends into the edge of the crust.

Brush the lattice with the egg yolk beaten with milk.

Bake for 45 to 50 minutes, until the crust is golden and the filling is set at the edges but still jiggles slightly in the center, reaching about 165 F / 74 C internally.

Cool the tart in the pan on a wire rack for 20 minutes, then remove the ring and cool completely at room temperature, about 2 hours, before slicing.