Skin, seed and cube the pumpkin. Roast in an oven at 200 degrees C until cooked; about 25 minutes.
In a large saucepan add the butter and olive oil then heat over a gentle moderate heat. Add the chicken, when white all over add the onion then cook until becoming transparent.
In a small saucepan add the chicken stock and thyme then bring to a simmer.
To the chicken add the rice and stir, when it has absorbed the butter and oil then add the wine. When the wine is absorbed add the chicken stock a ladle at a time, stirring after each ladle until absorbed.
When the rice is soft and the chicken stock gone stir in the Parmesan. Then add half the roast pumpkin and stir gently through.
Serve the risotto and then top with the remaining pumpkin.