A caramelized onion grilled cheese sandwich is a warm, comfort-food classic that brings together gooey cheese and rich, sweet onions between two slices of crispy bread. It’s pure delight in every bite!

This sandwich recipe addresses common issues like uneven flavors and insufficient richness, ensuring a delicious and satisfying grilled cheese experience for everyone.

Caramelized Onion Grilled Cheese Sandwich Recipe

I often find myself facing the challenge of creating something special for family dinners or casual gatherings. I’m always looking for ways to impress everyone, especially when I’m short on time and ingredients. This recipe ticks all the boxes, delivering beyond the ordinary grilled cheese.

What I love about this recipe is how straightforward it is despite its fancy vibe. You’ll spend a little over an hour making four satisfying sandwiches, featuring velvety cheese and flavorful onions that will leave your taste buds happy.

If you want to add a nice touch to your meal, try pairing them with my Grilled Cheese Sandwich for a classic side!

Why You Will Love This Recipe
Ingredient Notes
Recipe Baking Tips
Serving Suggestions
Recipe Variations
How to Store?
Other Recipes You’ll Love

Why You Will Love This Recipe

Rich and Savory Flavor , The caramelization of the onions brings out their natural sweetness, creating a rich, savory contrast with the gooey cheese that melts beautifully.
Comforting Texture , The crispy, golden-brown exterior of the grilled cheese sandwiches wraps around a warm, creamy filling, offering a delightful mouthfeel that’s satisfying and comforting.
Make-Ahead Convenience , You can prepare the caramelized onions ahead of time, allowing for quick assembly during busy weeknights or impromptu snack cravings without sacrificing flavor.
Versatile Ingredients , Feel free to switch up the jam or cheese used here. Experimenting with different combinations lets you create a personalized sandwich that suits your taste buds perfectly.

Caramelized Onion Grilled Cheese Sandwich Recipe

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Author: Charlene
Prep Time: 10 minutes
Cool Time: 0 minutes
Cook Time: 1 hour 5 minutes
Total Time: 1 hour 15 minutes
Yield: 4 sandwiches 1x
Category: sandwich
Method: pan frying
Cuisine: American
Diet: vegetarian

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Description

Delicious gourmet caramelized onion and brie grilled cheese sandwiches, perfect for a comforting meal.

Instructions

Step 1: Heat 2 tablespoons butter and 1 tablespoon olive oil in a large cast-iron skillet over medium-low heat. Add the peeled and sliced 1 pound yellow onions, stirring to coat the onions evenly in the butter and olive oil.
Step 2: Cook the onions for 40 to 45 minutes, stirring every 5 to 10 minutes. Monitor the color aiming for a deep golden brown, making sure the onions become tender and develop a rich sweetness.
Step 3: About 20 minutes into the cooking, if onions are not browning or begin sticking, add 1 tablespoon hot water to deglaze the skillet. Stir to lift caramelized bits to prevent burning. Continue cooking.
Step 4: If onions release water and appear watery toward the end of cooking, continue cooking for an additional 10 minutes without covering, stirring every 5 minutes until the moisture evaporates and onions thicken.
Step 5: Evenly spread 4 tablespoons blueberry jam on one side of 4 slices of bread.
Step 6: Spread a generous layer of 4 tablespoons Boursin cheese on one side of the other 4 slices of bread. Sprinkle 2 cups shredded mozzarella cheese on top of the Boursin spread.
Step 7: Place the jam-coated bread slices on top of the cheese-coated slices so that the jam and cheese sides face each other creating 4 sandwiches.
Step 8: Heat 2 tablespoons butter or margarine in the same skillet over medium heat until melted and foamy.
Step 9: Place two sandwiches in the skillet with the non-buttered side down. Cook for 4 to 5 minutes, or until the bottom is golden brown and a crust forms.
Step 10: Use a spatula to flip the sandwiches carefully. Cook the other side for 4 to 5 minutes more until golden brown and cheese melts thoroughly.
Step 11: If sandwiches feel soggy, replace Boursin with 2 tablespoons light cream cheese 5 to 10 minutes before serving for a drier filling. Adjust heat to medium if sandwiches do not brown evenly, checking 10 minutes into cooking.
Step 12: If bread tears during frying, gently press down on the sandwich with a spatula for 3-5 seconds after placing in skillet to improve cohesion.

Notes

Room Temperature: Store sandwiches in an airtight container at room temperature for up to 2 days to maintain texture and flavor.
Refrigeration: Keep sandwiches in an airtight container in the refrigerator for up to 5 days. Reheat before serving in a pan or oven.
Freezing: Wrap each sandwich tightly in plastic wrap, place in a freezer-safe container or bag, and freeze up to 2 months. Thaw overnight in the refrigerator before reheating.
Cook onions slowly over medium-low heat to develop full caramelization without burning—patience is essential.
Add hot water around 20 minutes into caramelization if onions stick or do not brown properly.
Stir onions regularly every 5-10 minutes to prevent scorching and ensure even cooking.
Use block cheese grated fresh for better melting over pre-shredded options.
To prevent sogginess, press sandwiches gently with a spatula after placing in the skillet and adjust heat as needed to medium.
If filling is too wet, substitute Boursin cheese with 2 tablespoons light cream cheese shortly before serving for a firmer texture.

Nutrition

Serving Size: 1 sandwich
Calories: 350
Sugar: 1g
Sodium: 600mg
Fat: 20g
Saturated Fat: 7g
Unsaturated Fat: 10g
Trans Fat: 0g
Carbohydrates: 15g
Fiber: 1g
Protein: 30g
Cholesterol: 90mg

Ingredient Notes

Sourdough bread: Go for a good quality sourdough loaf. It adds a lovely tang and texture. Look for a crusty exterior and a chewy interior for the best grilled cheese.
Onions: Sweet onions work great for caramelizing. Make sure they are firm and heavy for their size; this means they’re juicy and will cook down nicely. Yellow onions can be used too.
Cheese: A mix of sharp cheddar and creamy Gruyère creates a fabulous flavor and melt. Choose block cheese over pre-shredded for smoother melting.
Olive oil: A good quality extra virgin olive oil gives flavor and helps brown the bread perfectly. It’s great for sautéing the onions too for added richness.
Butter: Use unsalted butter for spreading on the bread. It gives that nice crunchy, golden exterior without overwhelming the filling’s flavors.
Sourdough bread: Go for a good quality sourdough loaf. It adds a lovely tang and texture. Look for a crusty exterior and a chewy interior for the best grilled cheese.
Onions: Sweet onions work great for caramelizing. Make sure they are firm and heavy for their size; this means they’re juicy and will cook down nicely. Yellow onions can be used too.
Cheese: A mix of sharp cheddar and creamy Gruyère creates a fabulous flavor and melt. Choose block cheese over pre-shredded for smoother melting.
Olive oil: A good quality extra virgin olive oil gives flavor and helps brown the bread perfectly. It’s great for sautéing the onions too for added richness.
Butter: Use unsalted butter for spreading on the bread. It gives that nice crunchy, golden exterior without overwhelming the filling’s flavors.

Recipe Tips

If onions aren’t browning, add 1 tablespoon hot water to deglaze the skillet during cooking, about 20 minutes in, to prevent sticking and burning.
When caramelized onions are watery, continue cooking for an additional 10 minutes without a lid, stirring every 5 minutes, until moisture evaporates.
If sandwiches aren’t browning evenly, check heat around 10 minutes into cooking; adjust to medium heat, ensuring a golden crust forms on both sides.
For sandwiches that feel soggy, use 2 tablespoons of light cream cheese instead of Boursin to create a drier filling, 5-10 minutes before serving.
If the bread tears when frying, gently press down on the sandwich with a spatula for 3-5 seconds after placing it in the skillet for better cohesion.

Serving Suggestions

Serve the caramelized onion grilled cheese with a side of roasted vegetable medley or a fresh arugula salad. Pair it with tomato basil soup or a creamy butternut squash soup for a comforting meal.

Use to make a savory caramelized onion and goat cheese bruschetta or a gourmet onion jam crostini. Add to a veggie-packed sandwich for a hearty lunch option.

Top with a drizzle of balsamic reduction or a smear of spiced aioli for an extra layer of flavor. Consider finishing it with fresh herbs or a sprinkle of garlic powder for added zest.

Recipe variations

You can use sourdough or whole wheat bread instead of sandwich bread to create different textures and flavor profiles in the caramelized onion grilled cheese sandwich.
Add 4 tablespoons of fig jam or apricot preserves as a substitute for blueberry jam to complement the sweetness of caramelized onions in this grilled cheese recipe.
Either Boursin cheese or cream cheese can be spread on the bread slices to offer a creamy, herby base for the cheeses and onions in this sandwich.
If serving more than four sandwiches, you can double ingredient amounts and cook the sandwiches in batches, using 8 tablespoons of butter for frying to maintain crispiness.

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How to Store?

To keep your caramelized onion grilled cheese sandwich fresh and delicious, follow these storage tips:

Room Temperature: Place sandwiches in an airtight container at room temperature up to 2 days to maintain texture and flavor.

Refrigeration: Store sandwiches in an airtight container in the refrigerator up to 5 days; reheat in a pan or oven before serving.

Freezing: Wrap each sandwich tightly in plastic wrap and place in a freezer container for up to 2 months. Thaw overnight in refrigerator.

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If you enjoyed this caramelized onion grilled cheese or any other recipe on my blog, please leave a ⭐ star rating and let me know how it went in the comments below. I appreciate taking time to read about this recipe, thank you!