Dice 250g pumpkin into 1cm-wide pieces. Place in a non-stick frypan with 1 tablespoon canola oil and cook over a medium to low heat.
Periodically toss and continue to cook until the pumpkin is cooked and the outside is darkened. Set aside.
Dice remaining pumpkin into large pieces and cook in 2 cups simmering water. When tender, puree the pumpkin with the water in which it was cooked. Add more water to bring the total pumpkin stock to 1 litre.
Heat 1 tablespoon of oil in a pan, add onion and garlic. Cook for 30 seconds.
Add rice. Toss for 1 minute and add 1 cup of pumpkin stock. Cook over a low heat.
As the liquid is absorbed, add another cup. Stir constantly and keep adding pumpkin stock as necessary. After 25 minutes, the risotto will be cooked.
Remove from heat and add the diced caramelised pumpkin and sage. Toss until well combined.
Season with salt and pepper and serve with shaved parmesan.