In a big pot heat up the olive oil and the butter. Braise the onion and the pumpkin dice slightly. Then add the chestnuts. Braise for a few minutes.
Add the rice and braise everything while constantly stirring.
Deglaze with the white wine.
Once the wine is absorbed, add the vegetable broth, always one ladleful. When that is absorbed, add the next ladle, etc.
Once you have added all the broth, take the pot off the stove.
Taste with salt and pepper. You can also add a little more butter.
Stir in the freshly grated Parmesan cheese.