French Onion Potato Gratin (Print Version)

Roasted Yukon Gold potatoes topped with slow-cooked onions and bubbling Gruyère cheese, a comforting French classic.

# What You'll Need:

→ Potatoes

01 - 4 large Yukon Gold potatoes, scrubbed and sliced into 1/2-inch rounds
02 - 2 tablespoons olive oil
03 - 1/2 teaspoon kosher salt
04 - 1/4 teaspoon black pepper

→ Caramelized Onions

05 - 2 large yellow onions, thinly sliced
06 - 2 tablespoons unsalted butter
07 - 1 tablespoon olive oil
08 - 1/2 teaspoon sugar
09 - 1/4 teaspoon salt
10 - 1 teaspoon fresh thyme leaves or 1/2 teaspoon dried

→ Topping

11 - 1 cup (100 grams) Gruyère cheese, grated
12 - 2 tablespoons fresh parsley, chopped (optional)

# How to Make It:

01 - Preheat the oven to 425°F. Line a baking sheet with parchment paper.
02 - Toss potato slices with olive oil, kosher salt, and black pepper in a large bowl. Arrange in a single layer on the prepared baking sheet. Roast for 25 to 30 minutes, flipping halfway through, until golden and tender.
03 - While potatoes roast, heat butter and olive oil in a large skillet over medium-low heat. Add sliced onions and salt. Cook, stirring frequently, until softened, about 10 minutes. Sprinkle sugar and thyme over onions, then cook, stirring occasionally, until deeply golden and caramelized, about 20 to 25 minutes more. Reduce heat if browning too fast.
04 - Remove roasted potatoes from the oven. Arrange potato slices in a shallow ovenproof dish or skillet, slightly overlapping.
05 - Evenly spread caramelized onions over the potatoes. Top with grated Gruyère cheese.
06 - Return the dish to the oven and bake for 10 to 12 minutes until cheese is melted and bubbling. Optionally, broil for 2 to 3 minutes to brown the top.
07 - Sprinkle chopped parsley over the top if desired and serve hot.

# Additional Tips::

01 -
  • It tastes like French onion soup but you can eat it with a fork and actually enjoy it without a spoon.
  • The Gruyère gets cratered and bronzed on top, which means crispy bits mixed with creamy melted goodness.
  • Your kitchen will smell so good that people show up thinking you've been cooking all day.
02 -
  • Onions need low, steady heat to caramelize properly—blasting them on high heat will burn them and taste bitter instead of sweet, and no amount of extra cooking fixes that.
  • Don't skip the halfway flip on the potatoes; it's the difference between crispy on both sides and one side that's pale and tender.
03 -
  • Use a mandoline or very sharp knife to slice potatoes evenly so they roast at the same rate and finish at the same time.
  • Don't crowd the potatoes on the baking sheet—they'll steam instead of roast if they're packed together, so use two sheets if needed.
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