French Onion Toast

Ingredients

• 4 tbsp (56 g)butter
• 3 lb (1.36 kg)onions, thinly sliced
• 1 largeshallot, thinly sliced
• a big pinch, plus more if neededkosher salt
• to tastefreshly cracked black pepper
• 2 tbsp (30 ml)sherry wine
• ½ cup (120 ml)beef stock
• 2 large sprigs, plus leaves to garnishfresh thyme
• 1bay leaf
• 6 large, thick slicesfresh sourdough bread
• 3 tbsp (42 g)butter, melted
• 12 oz (340 g)Gruyère cheese, shredded

Instructions

1. 1

   Caramelise the onions

   Heat a large, heavy-bottomed pot or Dutch oven over medium-high heat and melt the butter. Add the onions and shallot, season with a big pinch of salt and freshly cracked black pepper, and cook for 10 minutes, stirring often. Lower the heat to medium-low and cook for about 45 minutes, until deeply caramelised.

2. 2

   Reduce the mixture

   Raise the heat to medium and stir in the sherry. Simmer for 2 minutes, then add the beef stock, thyme sprigs and bay leaf. Bring to a simmer and cook for about 5 minutes, until most of the liquid has reduced. Taste and add more salt if needed, then remove the thyme and bay leaf.

3. 3

   Toast the bread

   Meanwhile, heat the oven to 200°C (400°F). Arrange the bread on a foil-lined baking tray and brush it with the melted butter. Toast for 10 minutes, then take it out and set the oven grill to high.

4. 4

   Add cheese and grill

   Spoon the onion mixture over the toast slices and top with the shredded Gruyère. Grill for 4–5 minutes, until the cheese has melted and the bread is golden brown, watching closely so it does not burn.

5. 5

   Finish and serve

   Cut the toast in half if desired. Finish with freshly cracked black pepper and fresh thyme leaves.

What is French onion toast?

This is a toast-based take on French onion soup, pairing slow-cooked onions with bread and melted cheese. The soup is associated with French cooking; this version turns its familiar onion, stock and cheese combination into a dish to eat by hand.

The long, gentle cooking makes the onions sweet and soft, while sherry and thyme add depth. Thick sourdough gives the topping a sturdy, crisp base.

Nutrition and macros by portion

The nutrition label shows one serving as written: 830 calories, 26g protein, 105g carbs, 49g fat.

The sourdough and onions provide most of the carbohydrates, while Gruyère and butter contribute much of the fat; the cheese also supplies most of the protein. Serve a smaller piece with a generous green salad or vegetables to balance the rich toast.

Why the onion choice matters

Onions: Thin slices cook down evenly and become tender as their moisture evaporates. The large quantity is intentional; they shrink substantially during cooking.

Shallot: A single shallot adds a mild, savoury note alongside the onions without overtaking them.

Caramelising takes patience

Start over medium-high heat for 10 minutes, stirring often, then turn the heat down to medium-low for about 45 minutes. The slower second stage helps the onions soften and brown rather than catch on the bottom of the pot.

Look for a deep golden-brown colour and a soft, jammy texture. If the pot starts to catch, stir well and keep the heat low.

Build flavour in the pot

Sherry: Simmer it for 2 minutes after stirring it into the onions, then add the stock. This gives the wine time to cook into the mixture.

Thyme and bay: Simmer the herbs with the stock for about 5 minutes, until most of the liquid has reduced. Remove the sprigs and bay leaf before topping the bread.

Toast before topping

Bread: Thick sourdough slices hold the onion topping and cheese. Brushing them with melted butter and toasting for 10 minutes helps the surface stay crisp beneath the moist onions.

Cheese: Spread the onion mixture across the slices before adding the shredded Gruyère. Grill for 4–5 minutes, keeping a close eye on the toast as the cheese melts and the edges brown.

Serve it while hot

The toast is best straight from the grill, finished with black pepper and fresh thyme leaves. Cut each slice in half for easier serving or smaller portions.

For a meal, serve it with a crisp green salad or simply dressed leaves to offset the rich cheese and buttery bread. Smaller pieces also work as an appetiser.

Recipe notes & tips

• Use a wide, heavy-bottomed pot so the onions cook in an even layer.
• Stir the onions regularly, especially as they become darker and softer.
• Shred the Gruyère evenly so it melts across the topping.
• Keep the toast in sight under the grill; the bread can brown quickly.
• Taste the onion mixture after reducing the stock and adjust the salt then.

Variations

• Add garlic: Stir finely chopped garlic into the onions near the end of their cooking.
• Use another cheese: Swap Gruyère for a similarly melting cheese with a savoury flavour.
• Skip the sherry: Leave it out and continue with the beef stock.
• Try vegetable stock: Use it instead of beef stock for a meat-free variation.
• Add mustard: Spread a thin layer of mustard on the toasted bread before adding the onions.

Common mistakes to avoid

• High heat throughout: The onions may catch before softening; reduce the heat after the first 10 minutes.
• Rushing the onions: They will lack the deep, soft finish; allow about 45 minutes at medium-low heat.
• Leaving excess liquid: The toast can become soggy; simmer until most of the stock has reduced.
• Using thin bread: It may struggle to hold the topping; choose large, thick slices.
• Walking away from the grill: The bread can burn quickly; watch it closely during the 4–5 minutes.

How to store

Store leftover onion mixture separately from the bread in a sealed container in the fridge for up to 3 days. Reheat the onions in a pan, assemble on fresh or leftover toast, and grill until hot and melted; assembled toast is best eaten straight away.

Frequently asked questions