Name a more classic sandwich than the iconic grilled cheese. I’ll wait… Okay fine, maybe peanut butter and jelly—but that’s certainly not as versatile as a beloved grilled cheese, with countless ways to personalize and elevate a dish that works for breakfast, lunch, dinner, and a midday snack alike. That said, I typically find myself wanting more than just sliced sandwich bread with American cheese (though that has its time and place, too). So when I heard mention of a “French onion soup grilled cheese,” I knew I’d be making this version on repeat. Why? Because caramelized onions, of course.
The humble onion is an ingredient we rely on for many uses. We chop one up for soups and stews, we dice one up for salsas and dips, and we slice one up for everything in between. But in my opinion—and I know I’m not alone—the best thing you can do with a bag of these versatile vegetables is to make caramelized onions.
An obvious way to highlight these beauties is in French onion soup, and that’s certainly something I make once in a while. More often than not, these sweet, umami-rich, melt-in-your-mouth morsels are the perfect way to upgrade otherwise ordinary dishes in a quick and easy way once I’ve made a big batch to keep in the fridge.
But my absolute favorite thing to do with caramelized onions is to turn the best part of French onion soup—the onion flavor-soaked toasty bread and gooey melted cheese—into an inspired grilled cheese that brings two gastronomic delights together.
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How To Make French Onion Soup Grilled Cheese
If French onion soup takes over an hour to make, a shortcut French onion soup grilled cheese takes about 15 minutes total, assuming the caramelized onions are already prepped. It takes fewer ingredients, too. Here’s the non-recipe recipe I use for the most delicious sandwich ever.
Step 1: Prep your bread and your pan. I prefer a hearty sourdough or French bread, but multigrain or rye works if that’s your pick. The slices should be about 1/4 to 1/2 inch thick. I butter the outside of my bread for crusty golden goodness, but I also add a swipe of mayo to the inside of one slice and a swipe of whole grain or Dijon mustard inside the other. Meanwhile, my cast iron griddle is heating up (though any skillet works for grilled cheese) with a healthy pat of butter to grease it.
Step 2: Pile grated Gruyère cheese and caramelized onions onto the sandwich. You can also use other types of cheese, like cheddar, mozzarella, or Swiss—or a combo—if Gruyère isn’t your thing.
Step 3: Toast the French onion soup grilled cheese in the buttered pan until golden brown and gooey, a few minutes on each side. Need more pointers? Check out these tips for perfecting your grilled cheese craft.
Recipe Tip
Before I close the sandwich up to send it to the pan, I add a drizzle of balsamic glaze (or a thick balsamic vinegar) on top of the onions and cheese to amp up the flavor. I’ll also sprinkle in some thyme when I have it.
What To Serve With French Onion Soup Grilled Cheese
I usually enjoy my French onion soup grilled cheese with a convenient side like chips, store-bought soup, or a simple side salad. It would also be lovely paired with miso soup or a beef bone broth dipper to really emulate the traditional dish—or even to evoke a French dip sandwich.
There are so many ways to easily upgrade the classic grilled cheese. But for now, French onion soup-style, oozing with sweet onion and nutty Gruyère is hard to beat. It has even made it into my list of top go-to meals—along with spaghetti and meatballs, lasagna, homemade pizza, and cheesecake. Because nothing beats comfort food. What other mashups should I try next?
