French onion soup is a cold-weather classic for a reason: The dish features a deeply savory, rich, slightly sweet broth topped with chunks of crunchy, toasted bread and blanketed with nutty, gooey, melted Gruyère. The only issue? Soup isn't always party-friendly: It's hard to hold a sloshy ramekin of hot broth while you're also trying to sip a cocktail and catch up with old friends.
Author and food stylist Maureen Petrosky has a solution. Her charming cookbook Après: 75+ Cozy Winter Recipes for the Perfect Post-Ski Gathering contains a recipe for French onion soup crostinis: "This version has all the good stuff, but is much less messy," Petrosky gushes. To make the dish, you'll caramelize onions until they're sweet and jammy, and drizzle them with red wine and chicken broth for depth. Then spread the onions onto toasted baguette slices — the soft, golden veg will pair perfectly with the crisp, buttery base. You finish everything off with a healthy handful of shredded cheese. Bake or broil the toasts until the Gruyère is melted to infuse every bite with salty, nutty richness.
French Onion Soup Crostini
Author: Maureen Petrosky
Prep Time: 15 min
Cook Time: 43 min
Calories: 220 calories per serving
Servings: 10 servings
Ingredients
- 2 tablespoons / 28g unsalted butter
- 4 cups / 480g sliced yellow or white onions
- 1⁄4 cup / 60ml red wine
- ½ cup / 120ml chicken broth
- ½ teaspoon kosher salt, plus more for sprinkling
- Freshly ground black pepper
- Cooking spray, for coating the pan
- 20 (½-inch / 1.3cm) slices French baguette
- ¼ cup / 56g butter, melted
- 1 garlic clove, peeled and halved
- 1 cup / 120g grated Gruyère or Swiss cheese
- 3 tablespoons finely chopped chives
Directions
- Preheat the oven to 425ºF / 220ºC.
- In a large cast-iron skillet or heavy-bottomed pot over high heat, melt the butter. Once foamy, add the onions and toss to coat. Turn down the heat to medium-high and stir occasionally until the onions are a deep golden brown and soft, 20 to 25 minutes.
- Add the wine and scrape up any brown (not black) parts from your pan. Cook the wine down
for 2 minutes. Add the chicken broth and cook for 3 to 5 more minutes, until the liquid is
almost gone. - Remove the onion mixture from the heat and season with the salt and pepper. Set aside.
- Spray a sheet pan with the cooking oil. Place the sliced baguette pieces on the pan in one layer. Brush with the melted butter and sprinkle with salt.
- Bake the baguettes for 8 to 10 minutes until golden brown and toasted. Remove the pan from the oven and let cool for 5 minutes.
- Rub the garlic clove over the top of each crostini. Top each crostini with 1 tablespoon of the
onion mixture, then add a generous topping of the Gruyère or Swiss cheese. - Return the pan to the oven and bake for 3 to 4 additional minutes, until the cheese is melted, bubbly, and golden brown. Remove the pan from the oven and transfer the crostini to a plate. Sprinkle with the chives and serve.
Text copyright © 2026 by Maureen Petrosky. Photographs copyright © 2026 by Erin Kunkel.
