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Ultimate Easy French Onion Potato Bake with Gruyère and Caramelized Onions

A thick, square slice of french onion potato bake showing layers of potatoes, creamy filling, and caramelized onions.
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Create a comforting side dish that tastes like French onion soup in potato form. This easy potato casserole uses simple ingredients for extraordinary flavor.

Ingredients

Scale
  • 2 tablespoons butter
  • 1 tablespoon olive oil
  • 2 large yellow onions, thinly sliced
  • 1 teaspoon salt, divided
  • 1/2 teaspoon black pepper, divided
  • 2 pounds Russet potatoes, peeled and thinly sliced (about 1/8 inch thick)
  • 1 cup beef broth
  • 1/2 cup heavy cream
  • 1 tablespoon Dijon mustard
  • 1 clove garlic, minced
  • 1 cup shredded Gruyère cheese
  • 1/2 cup shredded Parmesan cheese

Instructions

  1. Preheat your oven to 375 degrees Fahrenheit. Lightly grease an 8×8 inch baking dish.
  2. Make the caramelized onions: In a large skillet over medium heat, melt the butter with the olive oil. Add the sliced onions and cook slowly, stirring occasionally, for 20 to 25 minutes until they are deeply browned and soft. Add 1/2 teaspoon of salt and 1/4 teaspoon of pepper during the last 5 minutes. Remove onions from the skillet and set aside.
  3. Prepare the potato mixture: In a bowl, whisk together the beef broth, heavy cream, Dijon mustard, minced garlic, the remaining 1/2 teaspoon of salt, and 1/4 teaspoon of pepper.
  4. Assemble the bake: Arrange half of the thinly sliced potatoes in an even layer in the prepared baking dish. Top the potatoes with half of the caramelized onions and half of the Gruyère cheese. Pour half of the cream mixture evenly over the layers.
  5. Repeat the layering process: Add the remaining potatoes, followed by the remaining caramelized onions and Gruyère cheese. Pour the rest of the cream mixture over the top.
  6. Bake: Cover the dish tightly with aluminum foil. Bake for 45 minutes.
  7. Uncover and finish: Remove the foil. Sprinkle the top evenly with the Parmesan cheese. Return the dish to the oven, uncovered, and bake for another 15 to 20 minutes, or until the potatoes are tender when pierced with a fork and the top is golden brown and bubbly.
  8. Rest: Let the French onion potato bake rest for 10 minutes before slicing and serving.

Notes

  • For the best texture, slice your potatoes uniformly thin, about 1/8 inch. A mandoline slicer helps achieve this consistency.
  • If you do not have beef broth, you can substitute it with vegetable broth, though the depth of flavor will change slightly.
  • This dish works well as a hearty side dish for weeknight dinners or as a savory casserole for holiday gatherings.

Nutrition

Find it online: https://tastethisplate.com/french-onion-potato-bake-recipe/