For the soup
1 Take a heavy-bottomed pan and place over a medium heat and add the butter and olive oil. Add the chopped onions and cover with a lid for around 10 minutes until they begin to go soft.
2 Add the brown sugar, cover with the lid again and cook for a further 30 minutes until the onions begin to caramelise, but take care to ensure they don’t burn.
3 Add the crushed garlic, and cook for another few minutes. Sprinkle the flour over the onions and keep stirring. Slowly add the white wine and continue to stir until reduced.
4 Then add the hot beef stock gradually. Cover with the lid again and cook for approximately 20 minutes.
For the garnish
1 Pre-heat the oven to 160C/Gas
2 Cut around 24 very thin slices of the baguette. Lay the slices of bread on a baking tray and drizzle with olive oil. Season with salt and pepper. Place in the oven until lightly golden brown.
3 Serve with your choice of Gruyère or grated cheddar. You can serve the croutons and cheese on the side, or grill the cheese on top of the toast and place in the bowl of soup.
Like this? See also:
• Tom Kitchin and Dominic Jack recipes: Christmas dinner side dishes
• Tom Kitchin and Dominic Jack recipes: oysters with lemon beurre blanc