For the French onion soup, heat the olive oil in a pot. Cut the onion into fine rings and sauté in the oil until golden. Deglaze with white wine and add the soup. Season with salt and pepper.
Cook for about 30 minutes. Preheat the oven to 200 degrees. Cut the baguette into thin slices and rub with garlic. Spread the cheese on top and gratinate in the oven for about 10 minutes until golden brown. Arrange both together and serve the French onion soup.