- STEP 1
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.
- STEP 2
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.
- STEP 3
Bake the gratin for about the 20 minutes, or until bubbling and golden. Let it sit for a few minutes before serving.