Peel and roughly dice the onion and garlic. Heat the oil in a saucepan and fry the onions until translucent, sprinkle with sugar and caramelize briefly.
Briefly sauté the garlic, zucchini and potatoes, then deglaze with the cream and stock.
Season well, bring to the boil and finish cooking over medium heat. Before serving, puree the soup, stir in the parmesan and season again if necessary.
Freshly baked wholemeal baguette goes well with it.