Preheat oven to 165°C.

Line the oven dish with parchment paper along the bottom and the sides.

Peel the potatoes and rinse under cold water.

Add the butter to the saucepan and melt gently over a low heat on the stove.

Slice all the potatoes on the mandolin lengthways, approximately 2mm thick.

Place one layer of potatoes in the bottom of the oven dish, slightly overlapping the slices of potato to cover the entire surface of the oven dish.

Use the pastry brush to apply a thin coating of melted butter across the entire surface of your potato in the oven dish, then sprinkle a pinch of sea salt across the buttered potato.

Repeat the previous two steps, layering the potato, the melted butter and the sea salt, making sure you overlap the potatoes slightly so there’s no gaps and it creates a nice level layering, until you have used up all your potatoes.

Place a piece of baking parchment on top of the layered potato 'cake', and press down slightly.

Bake the potatoes, in the oven dish, for approximately 1 hour; check every 15 minutes. Use a small thin knife to check when the potatoes are cooked. Just poke your knife through all the layers of the potato, there should be no resistance.

Once the potatoes are cooked, place them in the fridge to cool down completely, minimum 6 hours; overnight is preferred. While they’re cooling, press them down with something heavy like a bottle of milk or a watermelon, just place a small tray on top beforehand. This will help the layers stick together.

Once the potato is completely chilled, carefully remove the potato from the oven dish and place onto your chopping board. Cut the potato cake into lengths, approximately 10cm by 4cm and 4cm tall.

Heat the vegetable oil in a frying pan over a medium heat on the stove, until the oil is approximately 180°C.

Carefully place a portion of potato into the oil and cook until golden brown on all sides. Take your time – this is where it will get really nice and crispy.

Remove from the frying pan, allow to drain on the paper towel and season generously with sea salt.