French Onion Grilled Cheese

Name: French Onion Grilled Cheese with Au Jus
Prep time: 15 min
Cook time: 1 h
Total time: 1 h 15 min
Yield: 4 servings
Cuisine: American
Ingredients: 5 medium white onions, thinly sliced; 3 tbsp olive oil, divided; 4 tbsp butter; salt, to taste; black pepper, to taste; 1 tbsp fresh thyme, chopped, plus more for au jus; 1 small shallot, quartered; 4 cups beef stock; 8 slices sourdough bread; 1/2 cup butter, melted for grilling; 1 tsp rosemary, finely chopped; 8 slices Swiss cheese

This French Onion Grilled Cheese transforms the classic soup into a crispy, melty sandwich by combining caramelized onions with Swiss cheese on buttered sourdough, served with a rich homemade beef au jus for dipping.

🌍American 🏷️French onion 🏷️Grilled cheese 🏷️Sandwich 🏷️Caramelized onions Swiss cheese

🏷️

🏷️Au jus

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TikTok

Total

1h 15m

Servings

4

Difficulty

Medium

Est. Cost

$23–$38

Recipe Source

View original recipe

From TikTok

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TikTok

Ingredients

5 medium white onions, thinly sliced
3 tbsp olive oil, divided
4 tbsp butter
salt, to taste
black pepper, to taste
1 tbsp fresh thyme, chopped, plus more for au jus
1 small shallot, quartered
4 cups beef stock
8 slices sourdough bread
1/2 cup butter, melted for grilling
1 tsp rosemary, finely chopped
8 slices Swiss cheese

12 Ingredients

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Instructions

1
To make the caramelized onions, heat 2 tablespoons of olive oil and 4 tablespoons of butter in a large pot over medium heat.
2
Add the thinly sliced onions and stir to coat them in the fat.
3
Season with salt and pepper and continue to stir.
4
Cook the onions low and slow, stirring occasionally, for about 45 minutes until they are deeply caramelized and golden brown.
5
Stir in the chopped fresh thyme and cook for another minute. Set aside.
6
To make the au jus, heat the remaining 1 tablespoon of olive oil in a separate pan. Add the quartered shallot and a few sprigs of fresh thyme.
7
Sauté for a moment until fragrant, then season with salt and pepper.
8
Pour in the beef stock and bring to a hard boil to infuse the flavors.
9
Strain the au jus through a fine-mesh sieve into a bowl. Discard the solids.
10
To assemble the sandwiches, combine the melted butter and chopped rosemary. Brush the rosemary butter on one side of each slice of sourdough bread.
11
Place four slices of bread, butter-side down, on a hot griddle. Top each with a slice of Swiss cheese.
12
Add a generous layer of caramelized onions on top of the cheese.
13
Top with another slice of Swiss cheese and the remaining slices of bread, butter-side up.
14
Grill, flipping once, until the bread is golden brown and crispy and the cheese is fully melted.
15
Remove from the griddle, cut in half, and serve immediately with the warm au jus for dipping.

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Tips & Notes

Pro tips

Don't rush caramelization—low to medium heat develops deep flavor. High heat browns the surface without sweetening the onions.
Slice onions evenly and thin for uniform caramelization and easier sandwich assembly.
Brush melted butter on the outside of the bread, not inside, to prevent soggy bread and ensure crispy golden exterior.
Have the au jus hot and ready before plating; serve immediately for best flavor contrast between sandwich and dipping sauce.

Substitutions

White onions → yellow or red onions (red onions are sweeter but may require 5 minutes less caramelization)
Sourdough bread → brioche or thick-cut white bread (brioche will be richer; white bread will be milder)
Beef stock → vegetable or chicken stock (reduces depth; use beef for best French onion flavor)

Storage & make-ahead

Store leftover au jus in an airtight container for up to 3 days. Reheat gently on the stovetop. Caramelized onions keep refrigerated for 5 days and can be frozen for up to 2 months. Grilled cheese is best eaten fresh but can be refrigerated and reheated briefly in a skillet.

Common Questions

How long does it take to caramelize the onions?

Caramelizing 5 medium onions typically takes 30-40 minutes over medium heat, stirring occasionally. They should be deep golden brown and sweet.

Can I make the au jus ahead of time?

Yes. Prepare the au jus up to 2 days ahead, store in the refrigerator, and reheat gently before serving.

What's the best way to get the grilled cheese crispy?

Use melted butter on the outside of the bread and cook over medium heat, pressing gently. Toast until golden brown on each side, about 3-4 minutes per side.