Heat the stock in a saucepan over a gently heat, it shouldn't boil as it will evaporate. Have it barely simmering.
In a large pan heat the remaining 1 tbsp of olive oil and 1 tbsp of butter over a medium heat.
Add the onions and cook gently for 10 minutes until very soft. Try not to get any color on them.
Add the garlic and cook for a further minute.
Add the rice, toss well with the onions for a minute or two.
Add the wine and let it reduce, stirring often.
Now is the time to start adding the stock, one ladle at a time, making sure the liquid has mostly been absorbed before adding another. You want the heat to be hot enough for a gentle sizzle but not so hot that the rice sticks to the bottom of the pan.
Keep adding the stock, stirring and pressing/massaging the rice (the rice grains rubbing together is what releases starch making it oozy and creamy).
From the first ladle it should take 20 mins to be done. You want the rice to still have a slight bite to it.
When you add your last ladle of stock add the pumpkin mixture and mix in thoroughly. Cook for a further 2 minutes.
Turn off the heat, add the parmesan and 1 tablespoon of butter to the top then cover with a lid if you can for two minutes. Then stir the melted parmesan through. It should be gloriously oozy and creamy!
Season to taste and serve with the crispy sage leaves on top and extra parmesan if you wish.