Cauliflower, caramelised onion and gruyere gratin

1.5kg cauliflower, trimmed and cut into florets
1/2 cup caramelised onions
1.5 cups pouring cream
1.5 cups grated gruyere
salt and pepper
2 tbsp extra virgin olive oil
12 sage leaves
finely grated parmesan to serve

Preheat oven to 180 C. Line 2x30cm round baking dishes with non-stick baking paper. Cut the cauliflower florets into 1cm thick slices and arrange in the dishes, placing teaspoons of caramlised onion between the overlapping slices. Drizzle with cream and top with the gruyere, salt and pepper. Bake for 30 mins or until the cauliflower is just tender and the cheese is golden.  While the gratin is baking, heat the oil in a small frying pan over medium heat. Cook the sage leaves, in batches, for 30 sec or until crisp. Top the gratin with sage leaves and parmesan to serve. Serves 8-10.