Heat the butter and oil until bubbling, add the onions and thyme.
Fry for 5 minutes, then reduce heat slightly and gently sauté the onions for +- 25 minutes until soft and sticky.
Add sherry and simmer for 2 minutes then add the flour and mix until well combined before adding the beef stock.
Cover and bring the boil, reduce heat and simmer gently for 25 minutes. Season to taste and add a squeeze of lemon juice if desired.
Meanwhile, preheat the oven to 200°C.Gruyere sticks:
Brush the sheet of pastry with egg and sprinkle evenly with thyme and cheese. Season with salt and pepper.
Use a spatula to gently flatten the cheese onto the pastry.
Slice into 9 strips then cut in half making 18 strips. Twist the strips one by one and place onto a large greased baking tray.
Bake for 15 minutes until golden and crispy.
Set oven grill and move the oven rack to the top shelf.
Spoon soup into oven proof dishes. Sprinkle with a generous amount of cheese and pop under the grill until golden and bubbling.
Serve immediately with Gruyere sticks.Recipe reprinted with permission of BitsOfCarey. To see more recipes, click here.