A winter comforter in one dish with pre-roasted butternut squash, leeks, ready prepared chestnuts, a subtle warming sprinkle of smoked paprika and topped with toasted walnuts for the crunch that cling to a layer of melted cheese.
Preheat the oven to 200°C/180°C fan/400°F/Gas 6.
Prick the butternut squash's skin and roast it whole (or pumpkin) in the oven for 15 minutes until the skin starts blistering. Remove and leave to cool slightly. Alternatively, prick the skin and put on high in the microwave for 10 minutes.
Heat the olive oil in a large non-stick frying pan and gently sauté the sliced leeks for about 10 minutes until softened. Set aside.
When the squash is easier to handle, peel off the skin and cut in 2 using a good knife. Remove the seeds with a spoon (don't discard) and cut the softened squash into rough chunks.
In a gratin dish, throw in the slightly softened squash chunks, the leeks and cooked chestnut.
Top the lot with the cheese, walnuts and parsley.
Bake in the oven for 30-35 minutes or until the cheese is bubbling and golden.
Serve with a good French baguette and a chilled white such as a Riesling from Alsace. If you can't find chestnuts, replace with fresh mushrooms that have been dry fried separately until they lose their juices (so beautifully concentrated in flavour).
I've added smoked paprika but if you prefer, add 100g of pre-fried lardons or bacon bits.