For the roasted butternut squash:
Preheat the oven to 180°C.
In a small saucepan or jug pour the recently boiled water over the dried mushrooms and seaweed. Leave to infuse for 30 minutes to create a light stock for the risotto.
While the stock is infusing, roast the butternut squash… On a large roasting tray toss the squash quarters and onion in the olive oil. Arrange the squash, skin-side down. Transfer to the oven and roast for 30 minutes.
Now add the garlic cloves and continue to roast for a further 10 minutes.
Add the hazelnuts and roast for a further 5 minutes.
Finally, add the sprigs of sage, toss them in the oil in the tray and return to the oven for 3-4 minutes, or until the sage is crisp and the hazelnuts are golden.
Remove the tray from the oven and leave to cool.
Drain the sage and hazelnuts on kitchen paper and keep to one side (as a garnish the risotto before serving).
Peel and finely chop the roasted onion and garlic.
Remove the flesh from the bottom third of the squash quarters and blend the flesh until smooth. (You might need to add 1-2 tablespoons of water to make it smooth.) Keep this butternut squash purée to one side – it will be added to the risotto at the end of cooking.
Carefully remove the flesh from the remaining butternut squash and roughly cut into 1cm dice and set to one side.
For the risotto:
In a medium saucepan on a medium heat, gently cook the rice in the olive oil for two minutes, stirring frequently so that the rice is evenly coated in the hot oil.
Now add the roasted, chopped onion and garlic.
Season with the salt and pepper and add 500ml of the dried mushroom-seaweed stock. Stir and continue to cook on the gentlest simmer. Only a bubble or two should break on the surface.
Cover the saucepan with a lid and cook for 20 minutes until the rice has absorbed all the stock.
At this stage the rice will be almost cooked. When you press a few grains between a thumb and finger there should be just a tiny core of uncooked white starch visible at their centre.
To create that desired creaminess we all love in a good risotto, stir with a wooden spoon with great vigour, adding the remaining stock, little by little.
By doing so you are extracting the starch from the rice, which will give it the most wonderful creaminess. Beware of not over-cooking the risotto. It only takes 1-2 minutes. You want the most unctuosity, creaminess and that slight chewy bite of the rice.
Finally, stir in half of the Saint Agur blue cheese, all of the butternut squash purée and the diced squash.
Add a squeeze of lemon juice and correct the seasoning to your taste.
Serve the risotto with the remaining Saint Agur blue cheese, hazelnuts, crispy sage and, if using, hazelnut oil.