For the soup, peel the onions, cut in half and cut into half rings. Melt the butter in a large saucepan and add the oil, salt and onions. Don't worry: it looks like too many onions at first. But that's exactly how it should be. Let the onions caramelize for at least 30 minutes over medium heat. The onions are ready when they are soft and golden brown.
When the onions are ready add the white wine and, with the help of the wine, carefully remove the roasted aromas from the bottom of the pot. Then add the flour, stir in and let simmer for 1 minute. Now add the broth, rosemary and thyme as well as the bay leaves and bring to the boil. Reduce the heat and allow to reduce for about 20 minutes. Then carefully season with salt and pepper. Finally add the cognac / brandy.
Preheat the oven to 200 degrees top / bottom heat. Cut the baguette into slices and rub over the surfaces with a halved and peeled clove of garlic. Put the soup in ovenproof soup bowls. Place the garlic bread on the surface and cover generously with the grated cheese. Put in the oven for a few minutes until the cheese has melted and the tops of the bread are slightly crispy. Good Appetite!