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French Onion Potato Casserole

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Potato Type: Russet
Cuisine: American


Side Dish

Prep Time

15 Mins

Cook Time

45 Mins


Serves 8


Creamy mashed potatoes topped with caramelized onions, fresh cracked black pepper, and baked until a gooey layer of provolone, gruyere, and parmesan cheese.



French Onion Potato Casserole

  • 6 cups (900g) Yellow Onions, peeled, sliced ¼ inch
  • 2 tablespoons (28.4g) Unsalted Butter
  • 2 teaspoons (2g) Salt
  • ½ tablespoon (3g) Freshly Ground Black Pepper
  • 1 quart (960ml) Vegetable Stock or Vegetable Broth
  • 2 tablespoons (30ml) Worcestershire Sauce (optional)
  • ½ teaspoon (~1g) Dried Thyme (Fresh Thyme can be subbed)
  • 1-1/2 pounds (0.68kg) Russet potatoes, peeled, diced 1-inch cubes
  • 8 ounces (226g) Provolone Cheese Slices
  • 4 ounces (113g) Gruyere Cheese, grated
  • ₁⁄₃ cup (30g) Parmesan Cheese, grated


  • As Needed Flakey Sea Salt (such as Maldon)
  • 1 teaspoon Fresh Thyme Leaves


  1. Preheat the oven to 375 F (190 C).
  2. Peel and slice the onions about ¼ inch thick. In a heavy bottomed pot over medium high heat. Melt the butter and add the onions. Cook the onions for 2-3 minutes or until they are slightly translucent. Add the salt and pepper and continue to cook the onions until they begin to caramelize. At this stage its import to stir the onions regularly so they do not burn. Once the onions take on an even dark brown color (about the color of milk chocolate and should take about 20 minutes) add the vegetable stock, Worcestershire sauce, and thyme, scraping the bottom of the pan to release any caramelized flavor. Reduce the heat and allow the sauce to simmer for about 5 minutes.
  3. Stir in the diced potatoes and remove from the heat.
  4. Spray a piece of aluminum foil with nonstick spray. Place the foil (oiled side down) over the casserole and place in the preheated 375 F (190 C) oven for 25 minutes. Remove the aluminum foil and arrange the cheese in the following order: take half the provolone slices and arrange them on the top in an even layer, follow with the shredded gruyere, grated parmesan, and another layer of the provolone (off set the provolone so the second layer fills any gaps from the first). Bake the casserole for an additional 10-12 minutes or until the cheese is bubbly, potatoes are tender, and the top is golden brown.
  5. Remove the casserole from the oven and garnish with the fresh thyme and flakey salt.
  6. Enjoy right away, its ok to burn your mouth, it’s part of the fun and a crucial part of the experience.

2 Reviews

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I made this! It was really good. I don't think I had enough onions, I used maybe about 7 yellow onions....Read Full Review



I made this! It was really good. I don't think I had enough onions, I used maybe about 7 yellow onions. 35 minutes was not enough time to cook the potatoes through, so I left it in a while longer. It was very soupy and the cheese on top was way too much. I tried mixing it in but all the cheese congealed into weird chunks through out, so maybe less cheese, or a roux next time. Still, did not deter me from devouring this! Definitely going to remake this but a lil different next time


There is NO WAY the potatoes are going to be fully cooked in the 35-37 minute cook time in a 375...Read Full Review



There is NO WAY the potatoes are going to be fully cooked in the 35-37 minute cook time in a 375 degree oven… especially in 1” cubes. Maybe if they’re pre-boiled/blanched.

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