Onion and fennel gratin

Preheat the oven to Gas 6, 200C, 180C fan. Bring a pan of water to the boil, add the fennel and onions and cook for 5 minutes, or until tender. Drain and tip into a large baking dish.

Mix the creme fraiche and chicken stock, and season with pepper, salt and grated nutmeg. Spoon the sauce over the vegetables then scatter over with the grated Parmesan cheese.

Bake the gratin for about the 20 minutes, or until bubbling and golden. Let it sit for a few minutes before serving.