French Onion Soup Grilled Cheese with Gruyère Crust Tips, FAQ & printable recipe

Tips for success

To get the perfect cheese pull, make sure the cheese is fully melted before you remove the sandwich from the skillet. If the cheese isn't melting, cover the skillet with a lid for a minute to trap the heat. Use a spatula to press down gently on the sandwich to encourage even melting and browning.

For an extra crispy crust, you can add a little more Parmesan to the skillet before placing the sandwich down. This creates a lacy, crispy edge that is irresistible.

Also, don't skip the resting time — it allows the cheese to set slightly, making the sandwich easier to slice and more enjoyable to eat.

Variations

• Add Caramelized Shallots: Replace half of the onions with thinly sliced shallots for a sweeter, more delicate flavor. Caramelize the shallots alongside the onions, following the same method.
• Spicy Kick: Add a pinch of red pepper flakes to the mayonnaise or a few slices of pickled jalapeños to the sandwich for a spicy twist that balances the richness.
• Herb-Infused Mayo: If garlic herb mayo isn't available, mix plain mayonnaise with a minced garlic clove and a teaspoon of chopped fresh chives or parsley.
• Bacon Addition: Cook 4 slices of bacon until crisp and add them to the sandwich for an extra smoky, savory layer. This is optional and adds a few minutes to the cooking time.

Storage and make-ahead

Fridge

Store leftover sandwiches in an airtight container in the refrigerator for up to 2 days. Reheat in a skillet to restore crispness.

Freezer

Freeze assembled but uncooked sandwiches in a single layer on a baking sheet, then transfer to a freezer bag.

Reheat

Reheat refrigerated sandwiches in a skillet over medium heat for 2-3 minutes per side until hot and crisp.

Store any leftover sandwiches in an airtight container in the refrigerator for up to 2 days. To reheat, place them in a skillet over medium heat for a few minutes per side until warmed through and crisp. Avoid microwaving, as it will make the bread soggy.

The caramelized onions can be made up to 5 days ahead and stored in the refrigerator. You can also assemble the sandwiches (without cooking) and wrap them tightly in plastic wrap, then refrigerate for up to 24 hours.

When ready to cook, simply griddle them as directed, adding a few extra minutes to the cooking time.

Serving ideas

Serve these sandwiches hot, straight from the skillet, with the cheese pulling in long, gooey strands.

They are perfect on their own for a satisfying dinner, or paired with a simple green salad dressed with a light vinaigrette to cut through the richness. A bowl of tomato soup would also be a classic companion.

For a more indulgent meal, serve the grilled cheese with a side of roasted vegetables or a cup of French onion soup for dipping.

The crispy Parmesan crust and melted cheese make this a crowd-pleaser that's sure to become a favorite. Enjoy it while it's warm and the cheese is at its most stretchy.

Frequently asked questions

Recipe card

French Onion Soup Grilled Cheese with Gruyère Crust

Prep 15 minCook 25 minTotal 40 minServes 2

Ingredients

• 3 cups caramelized yellow onions
• 2 tbsp dry sherry
• 2 tbsp beef stock
• 1 tsp fresh thyme leaves
• 3/4 cup shredded Comté cheese
• 3/4 cup shredded Gruyère cheese
• 4 slices thick country sourdough bread
• 1/4 cup garlic herb mayonnaise
• 1/2 cup grated Parmesan cheese
• 2 tbsp unsalted butter, for the skillet

Instructions

1. In a large cast-iron skillet over medium heat, melt 1 tablespoon of butter. Add the sliced onions and cook, stirring occasionally, until deeply golden and caramelized, about 20 minutes. If they start to stick, add a splash of water. Once the onions are richly browned, add the dry sherry, beef stock, and fresh thyme leaves. Cook for 1 to 2 minutes, scraping up any browned bits, until the liquid is mostly absorbed. Remove from heat and set aside.
2. Shred the Comté and Gruyère cheeses if not already shredded. Combine them in a bowl. Spread the garlic herb mayonnaise evenly on one side of each sourdough slice. Sprinkle the grated Parmesan onto a plate and press the mayonnaise-coated side of each bread slice into the Parmesan, creating a crust.
3. Place two slices of bread, Parmesan-side down, on a clean work surface. Divide the caramelized onion mixture evenly between the two slices. Top with the shredded Comté and Gruyère mixture. Place the remaining bread slices on top, Parmesan-side up, to form two sandwiches.
4. Heat the same cast-iron skillet over medium heat and add the remaining butter. Once the butter is melted and sizzling, place the sandwiches in the skillet. Cook for 3 minutes per side, pressing down gently with a spatula, until the bread is golden brown and the cheese is melted. If the bread browns too quickly, reduce the heat slightly.
5. Remove the sandwiches from the skillet and let them rest for 2 minutes on a cutting board. This allows the cheese to set slightly and prevents it from running out when slicing. Use a sharp knife to cut each sandwich in half, revealing the gooey, stretched cheese pull.

Contains: gluten, milk, eggs, sulfites

Estimated nutrition per serving

Calories

680

Protein

28 g

Carbohydrates

45 g

Fat

42 g

Automatic estimate from the ingredient list, not laboratory-verified.