Peel the onions then cut them in half, slice them into half-moons as finely as possible (I use a mandolin)
Over a low heat, melt the butter in a large, heavy bottomed pan, add the sliced onions and season with salt and pepper
On a low heat, cook the onions until they turn a deep walnut colour. Stir them regularly as you do not want the onions to burn. This is the most important part of the recipe as burnt onions will ruin the soup. The onions may take up to an hour to cook.
Add the flour and thyme, stir for a couple of minutes (making sure the flour doesn’t catch on the base of the pan and burn)
De-glaze the pan with the vinegar and half the wine, simmer for a couple of minutes, add the remaining wine and beef stock, bring the soup to a boil.
Reduce the heat, partially cover and simmer for an hour, after which add the brandy and check for seasoning.
Brush the baguette slices with the melted butter and lightly toast on both sides.
When ready to serve, ladle the soup into ovenproof soup dishes, top with the prepared croutons and cover with a generous heap of cheese. Place in a preheated grill and cook until golden.
Recipe reprinted with permission of The Muddled Pantry
. To see more recipes, please click here
To receive quick and convenient weekday recipes, join our Easy Weekday Meals mailing list, and for up-to-date trending food, restaurant and wine news subscribe to our Editor’s Weekly newsletter.