French Onion Casserole


The irresistible creaminess of mac and cheese marries the richness of French onion soup in this baked pasta recipe.

French Onion Soup Casserole
Photo: Antonis Achilleos
Hands On Time:
35 mins
Total Time:
1 hrs

This casserole is a delicious and slightly more refined take on classic mac and cheese. Start by infusing penne with rich, custardy flavor by cooking it in a mixture of cream and stock. Then coat the pasta in a thick sauce of jammy caramelized onions mingled with Gruyere and cheddar. Make-ahead tip: Assemble the dish up until the baking step; let it cool, cover, and store in the refrigerator for up to two days. Bring to room temperature before baking.


  • Cooking spray

  • 3 tablespoons olive oil

  • 2 large sweet onions, thinly sliced (about 7 cups)

  • 1.50 teaspoon kosher salt, divided

  • 2 teaspoon apple cider vinegar

  • 2.50 cups heavy cream

  • 2 cups unsalted vegetable stock

  • 1 16-oz. pkg. penne rigate or ziti pasta

  • 1.50 tablespoon Worcestershire sauce

  • teaspoon ground nutmeg

  • 1 medium clove garlic, grated

  • 12 ounces aged Gruyère cheese, shredded (about 3 cups), divided

  • 4 ounces sharp white Cheddar cheese, shredded (about 1 cup), divided

  • 1 tablespoon fresh thyme leaves


  1. Preheat oven to 350°F with 1 rack in center of oven and 1 rack 6 inches from heat. Lightly coat a 13-by-9-inch broiler-safe baking dish with cooking spray.

  2. Heat oil in a large skillet over medium-high. Add onions and 1/2 teaspoon salt; cook, stirring occasionally, until onions begin to soften, about 5 minutes. Reduce heat to medium; cook, stirring occasionally, until onions are deep golden brown and jammy, 15 to 18 minutes (add 1/4 cup water at a time if onions start to burn). Remove from heat and stir in vinegar.

  3. Meanwhile, add cream and stock to a medium saucepan. Bring to a simmer over medium-high. Add pasta; simmer, stirring occasionally, until just al dente, 8 to 10 minutes. Stir in Worcestershire sauce, nutmeg, garlic, and remaining 1 teaspoon salt. Remove from heat. Add 2 1/2 cups Gruyère and 1/2 cup Cheddar, a handful at a time, stirring until melted between additions.

  4. Stir half of caramelized onions into pasta mixture. Transfer to prepared baking dish and top with remaining caramelized onions. Sprinkle with remaining 1/2 cup each Gruyère and Cheddar. Bake on center rack until bubbly, about 20 minutes. Transfer baking dish to top rack and increase oven temperature to broil. Broil until cheese is golden brown, about 3 minutes. Remove from oven and sprinkle with thyme. Let cool for 10 minutes before serving.

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