Heat the oil and sauté the onion and thyme. Add the rice and sauté, stirring, until translucent. Add the wine and reduce completely. Pour in the stock little by little; the rice must be covered with a small amount of stock at all times. Cover the rice and simmer, stirring, for approx. 15 mins. over a medium heat. Remove the thyme. Add the courgette, simmer for about another 4 mins. Stir in the gorgonzola and season the risotto.