Step 1

Brush a 23 x 30cm (2L) capacity baking dish with butter to lightly grease.

Step 2

Place the potato, milk, cream, thyme and nutmeg in a large saucepan. Season with salt and pepper. Bring to the boil slowly over medium heat. Reduce heat to medium-low and simmer gently for 5 minutes or until the potato is slightly tender.

Step 3

Arrange half the potato mixture over the base of the prepared dish. Top with the onion. Spread the remaining potato mixture over the top and press down slightly. Cover with foil. Bake in oven for 30 minutes. Uncover and bake for a further 15-20 minutes or until golden. Set aside for 2 hours to cool completely. Cover and place in the fridge overnight to chill.

Step 4

Preheat oven to 200°C. Line a baking tray with non-stick baking paper. Cut the potato gratin into 8 portions. Transfer to the lined tray.

Step 5

Sprinkle with the parmesan. Bake in oven for 15-20 minutes or until heated through. Serve.