French Onion Grilled Cheese Sandwiches


Former F&W food editor Grace Parisi reinvented the classic grilled cheese sandwich with this version, which emulates the gooey, cheese-y top of a bowl of French onion soup. Give yourself time to cook the onions slowly; caramelized onions take almost an hour to achieve their sweet flavor and melty texture, but are worth the wait. The Dijon mustard and pickle slices help cut the richness of this sandwich and keep it from feeling too heavy.  More Grilled Cheese Recipes

Grilled Gruyère and Sweet Onion Sandwiches
Photo: © Yunhee Kim
Active Time:
30 mins
Total Time:
1 hr


  • 3 tablespoons unsalted butter, softened

  • 1 tablespoon extra-virgin olive oil

  • 1 large onion, halved and thinly sliced crosswise (4 cups)

  • Salt and freshly ground pepper

  • Eight 1/2-inch-thick slices of whole-grain bread

  • Dijon mustard

  • 8 ounces imported Gruyère cheese, thinly sliced

  • 2 half-sour pickles, thinly sliced lengthwise


  1. In a deep skillet over medium-high, melt 1 tablespoon of the butter in the oil. Add onion, cover and cook, stirring once or twice, until softened, about 5 minutes. Uncover and cook over medium, stirring occasionally, until onion is very tender and caramelized, about 35 minutes longer. Add water to the skillet as necessary, 1/4 cup at a time, to prevent onion from scorching. Season caramelized onions with salt and pepper.

  2. Spread bread with the remaining 2 tablespoons of butter and arrange, buttered side down, on a work surface. Spread a thin layer of mustard on each slice. Top half of the slices with onion, Gruyère and pickles and close sandwiches.

  3. Preheat a skillet or panini press. Grill sandwiches over low heat until bread is toasted and cheese is melted, about 10 minutes. If using a skillet, press sandwiches with a spatula and flip them halfway through. Cut in half and serve right away.

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