Hazelnuts, filberts and cobnuts – they all are, in essence, the same thing. A cobnut (or filbert) is a cultivated hazelnut that is usually sold fresh rather than dried. The vibrant green leafy husks and the green shells are the hallmark of the cobnut. The nuts will be ready to pick in September and October but the cultivated cobnut can also make an appearance in the supermarkets and greengrocers, as early as August.
The flavour of cobnuts changes significantly as the nut matures. When just picked they are sweet, fresh and creamy, but as they mature or when they are roasted the flavour becomes deeper, with hints of caramel and a more earthy flavour. The cobnuts really do add an extra dimension to this simple crumble.
SERVES 4 AS A MAIN COURSE OR 6–8 AS A SIDE DISH
For the filling
2 tbsp olive oil
3 banana shallots , cut in half lengthwise and sliced
2 cloves of garlic, crushed
500g chestnut mushrooms, sliced
500g trimmed leeks, sliced into ½-cm slices
500ml vegetable stock (Basics p. 284)
100ml dry white wine
1 tsp Dijon mustard
75g crème fraîche
1 tsp cornflour, slaked in 1 tbsp cold water
Maldon sea salt and freshly ground black pepper
For the crumble
100g plain flour
1 tsp Maldon sea salt, finely ground
50g oatmeal
65g unsalted butter
50g cobnuts, chopped
50g Parmesan, grated
freshly ground black pepper
To serve
a crisp salad with a sweet mustardy dressing
or some pork chops, a crisp-skinned chicken or a roasted pheasant.
1. Preheat the oven to 170°C.
2. Sweat the shallots and garlic in the olive oil until tender. Add the mushrooms and cook over a high heat for a couple of minutes. Stir in the leeks and add 100ml of the stock. Place a lid on the pan and reduce the heat, cooking for approximately 5 minutes until the leeks are tender. Remove the lid of the pan and cook over a high heat until the mix is fairly dry.
3. In a separate saucepan, reduce the wine to a syrup and then add the remaining stock. Reduce to around 250ml then add the mustard, crème fraîche and season to taste. Thicken with enough cornflour to achieve a thick double cream consistency. Add the sauce to the leek mix and check the seasoning. Transfer to an ovenproof dish or dishes.
4. For the crumble mix, sift the flour and salt into a bowl and stir in the oats. Rub in the butter and then mix in the cobnuts and Parmesan. Season with black pepper. Scatter the crumble mix over the leek base and bake for 20–30 minutes until the top is golden brown.