To make the Pasta Brisè (shortcrust pastry dough), combine the flour, butter and salt in a bowl. Use your fingertips to rub the butter into the flour until the texture resembles fine breadcrumbs. Add the milk and egg and mix by hand until the dough just starts to come together.
Turn the Pasta Brisè dough onto a clean, lightly floured work surface. Lightly knead to bring together. Gather the dough with your hands to form a ball. Wrap in plastic wrap (cling film) and refrigerate for 30 minutes.
Preheat the oven to 200°C conventional oven/ 180°C fan-forced (400° Fahrenheit/Gas 6).
Heat the olive oil in a large frying pan over medium heat. Add the garlic and cook for 1 minute, then add the spinach. Season with salt to taste. Cook until the spinach wilts. Allow to cool, then squeeze out excess moisture. Roughly chop the spinach.
Grease a 24cm round, tart tin or cake pan with butter. Remove the Pasta Brisè (shortcrust pastry dough) from the fridge and turn onto a large sheet of baking paper. Use a rolling pin to roll out the Pasta Brisè. It should be large enough to fit the base and sides of the tin. Flour the rolling pin well and gently roll up the pastry dough around the rolling pin. Unroll the pastry dough into the tart tin or cake pan. Gently push the pastry a little above the edge of the tin. Use a fork to prick the base all over.
Cover the base of the Pasta Brisè with a sheet of baking paper and top with baking beads (alternatively use beans or rice). Bake for 10 minutes, then carefully remove baking paper and baking beads. Bake for a further 5 minutes then remove from the oven.
Meanwhile to make the filling, use a fork to combine the eggs, melted butter and parsley. Season with sea salt to taste.
Spread half of the spinach mixture onto the blind-baked Pasta Brisè pastry. Pour half of the filling over the spinach mixture. Sprinkle half of the Parmigiano Reggiano, ham and Provolone cheese over the filling. Repeat using the remaining spinach, Parmigiano Reggiano, ham and Provolone cheese. Bake for 35 minutes or until cooked through.
Allow to cool for 5 minutes before removing the Torta salata di spinaci (spinach tart) from the tart base. Cut into 4 wedges to serve – buon appetito.