2 cups chicken stock
1 red onion, thinly sliced
1 1⁄2 kilograms kumara, peeled and sliced 1⁄2 cm thick, we used Beauregard
1 tablespoon fresh thyme leaves
2 cloves garlic, crushed
a good grating of fresh nutmeg
1 teaspoon sea salt
freshly ground pepper
1⁄2 cup freshly grated Parmesan cheese
Preheat the oven to 200°C. Lightly grease a 25 x 35 cm Swiss roll tin.
Gratin: Place all the ingredients in a large saucepan and bring to the boil. Simmer gently for 10 minutes. Use a slotted spoon to transfer the kumara to the Swiss roll tin and spread to an even layer. Pour over the stock and onions, spreading them out evenly.
To cook: Dot the gratin with butter and sprinkle with Parmesan cheese. Bake for 25 minutes or until the kumara is tender, the top is golden and most of the stock has been absorbed.
The gratin can be cooked 1 day ahead. Cool, cover and refrigerate in the tin. Cover with aluminium foil when reheating.