Artichoke Tart - Torta di carciofi

Pastry

• 100 g Parmesan cheese cut in pieces (2 cm)
  or vegetarian hard cheese cut in pieces (2 cm)
• 200 g plain flour plus extra for dusting
• 1 pinch fine sea salt
• 100 g unsalted butter cold, diced
• 50 g milk
• 1 egg white lightly beaten

Filling

• 100 g onions quartered
• 2 garlic cloves
• 30 g unsalted butter diced
• 100 g frozen spinach defrosted, drained
• 2 medium eggs
• 2 egg yolks from medium eggs
• 250 g double cream
• 1 tsp fine sea salt
• 1 pinch ground black pepper
• 100 g large black olives pitted
• 480 g tinned artichoke hearts large, drained, halved (drained weight)