Cut the pumpkin in half and scoop out the seeds. Place it in a roasting dish, drizzle over the olive oil, and sprinkle with salt and pepper. Roast for 55-60 minutes at 180°C or 350°F and set aside to cool a little.
Cut the shallot in half, peel it and then dice it as finely as you can.
Dice the celery as finely as you can.
Peel the garlic and dice it as finely as you can.
Cut the sage leaves into thin strips.
Heat the vegetable stock to a slow simmer.
Heat a 28cm or 11" frying pan or skillet over a medium-high heat and add the butter. When the butter begins to foam, add the diced shallot and celery, then cook until softened.
This will take around 4-5 minutes. If they begin to colour, reduce the heat a little.
Add the garlic and cook for 1 minute.
Pour in the risotto rice and stir until the grains become translucent at the edges.
This should take 2-3 minutes.
Add the shredded sage, pour over the white wine and stir until almost all of the wine has evaporated/been incorporated into the rice.
Turn the heat down a little and slowly stir in the hot vegetable stock a ladleful at a time. Stirring continually, making sure almost all of the stock has been incorporated each time, and the pan is almost dry. As you get to the end of the cooking process, you can add more stock at a time.Repeat this until all of the stock is incorporated and the rice is cooked with a very slight bite.
This should take between 25 and 35 minutes.
Whilst the rice is cooking, scoop the roasted squash from the skins, which should be cool enough to handle now, and mash with a fork to form a puree.
It should yield around 300g or 1 cup of roasted butternut squash puree.
Stir the squash puree into the risotto and cook until it is all incorporated and creamy, then remove from the heat and add a lid, letting the dish sit for 5 minutes.
Whilst the risotto is relaxing crumble the Roquefort cheese, then serve the risotto topped with the crumbled cheese.