Preheat an oven to 200 degrees C. When hot add the carrots, pumpkin and potatoes then roast for 25 minutes or until cooked through but still firm.
Meanwhile, in a small saucepan add the chicken stock and thyme then bring to a simmer.
In a large saucepan add the butter and olive oil then heat over a gentle moderate heat. Add the onion then cook until becoming transparent.
To the onion add the rice and stir, when it has absorbed the butter and oil then add the wine and mushrooms. 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 roasted vegetables and Parmesan cheese.