Preheat the oven grill (electric oven: 200 °C/circulating air: 175 °C/gas: see manufacturer). Peel and halve onions and cut them into strips. Fry bacon in a large pan until crispy. Take out. Heat oil in the bacon fat.
Brown the onions in it. Sprinkle with sugar and caramelise briefly while stirring. Season with salt and pepper.
Deglaze onions with approx. 1⁄2 l water and wine, bring to the boil. Add broth and thyme. Simmer for about 10 minutes. Meanwhile roast bread in the toaster, then dice roughly. Remove rind from cheese and cut into wide strips.
Season soup with salt, pepper and paprika. Pour into four ovenproof soup bowls. Place on a baking tray. Spread bread cubes on the soup, cover with cheese and bake under the hot grill for 3-4 minutes.
Sprinkle with bacon and serve immediately.