Peel onions and cut them into rings. Heat the oil. Stew the onions in it at low heat for about 15 minutes until soft, without them turning brown. Dust with flour. Deglaze with stock and white wine, season with salt and pepper
Simmer covered soup for about 15 minutes, season again. Cut the baguette into slices and spread on a baking tray lined with baking paper. Grate cheese finely and spread on the slices of bread
Bake in a preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: see manufacturer) for 5-7 minutes. Wash parsley, shake dry, pluck leaves from the stalks and chop finely. Arrange soup and bread slices in soup bowls and sprinkle with parsley