Heat 1 tablespoon oil and 15g butter in a medium saucepan over medium heat. Add carrots and mix well with a wooden spoon, until the carrots are evenly coated with oil. Add 125ml water, a bit of salt and sugar, cover and cook for about 5 minutes until the carrots are tender.
Uncover and continue cooking for a few minutes while stirring constantly until all the liquid has evaporated and the carrots just start to brown. Take out carrots, set half of them aside and puree the other half with 150ml hot water in the food processor. Leave pot as is.
Pour chicken stock in a separate pot, cover and simmer over low heat.
Add the remaining oil and remaining butter into the pot where the carrots were cooked and heat. Add onions and saute for 3 minutes until soft and translucent. Add rice and stir for 1 minute with a wooden spoon, so rice is well coated with oil. Add wine and cook while stirring constantly until all the wine has been absorbed.
Stir in carrot puree and cook until it thickens and no longer looks like soup.
Add 125ml chicken stock and stir until almost all liquid has been absorbed. Add the next 125ml chicken stock and stir. Continue until all most of the stock is used up and the rice is cooked al dente, about 20 minutes. You should have at least 250ml chicken stock left.
Add the remaining carrots (keep a few for garnish). Then stir in mascarpone, Parmesan, 1 tablespoon parsley and thyme. Add the rest of the chicken stock (upto 250ml) in small amounts in order to make the risotto more liquidy. Season with salt and white pepper.
Plate risotto and sprinkle with Parmesan, 1 tablespoon of parsley and carrot pieces. Serve immediately.