Method

• 1.
  Preheat the oven to 200°C.
• 2.
  Combine pecorino and parmesan and 21/2 tsp freshly ground black pepper in a bowl. Place cream and garlic in a small saucepan over medium heat and bring to a simmer. Remove from heat, add 1/2 tsp salt flakes and set aside.
• 3.
  Finely slice potatoes (we used a mandoline) to 2mm thick. Layer one-third potato in a 4-cup (1L) greased baking dish. Pour over one-third cream mixture and scatter over one-third cheese mixture. Repeat layering process, finishing with a layer of cheese. Scatter over Gruyere. Cover with foil, place on a baking tray and bake for 1 hour or until potato is tender when pierced with a sharp knife. Remove foil and bake for a further 15 minutes or until golden and bubbling. Cool slightly before serving.