Onions peel, quarter and in fine rings cut. Peel garlic and chop finely. Heat the oil in a large pot. Sauté onions and garlic in it. Dust with paprika, deglaze with broth, bring to the boil and simmer covered for about 20 minutes.
Remove the rind from the cheese and grate finely. Wash parsley, dab dry and chop finely. Add wine and parsley to the soup, season with salt, pepper and sugar. Pour the soup into 4 ovenproof soup bowls, place a slice of bread in each and sprinkle with the cheese.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes. Remove from the oven and serve immediately.