French Onion Potato Slices (Printable)

Roasted potato slices topped with caramelized onions and bubbling Gruyère cheese for rich, savory flavor.

# What You Need:

→ Potatoes

01 - 4 large Yukon Gold potatoes, scrubbed and sliced into ½-inch rounds
02 - 2 tablespoons olive oil
03 - ½ teaspoon kosher salt
04 - ¼ teaspoon black pepper

→ Caramelized Onions

05 - 2 large yellow onions, thinly sliced
06 - 2 tablespoons unsalted butter
07 - 1 tablespoon olive oil
08 - ½ teaspoon sugar
09 - ¼ teaspoon salt
10 - 1 teaspoon fresh thyme leaves or ½ teaspoon dried thyme

→ Topping

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

# How-To Steps:

01 - Preheat the oven to 425°F. Line a baking sheet with parchment paper. Toss potato slices with olive oil, salt, and pepper in a large bowl. Arrange in a single layer on the baking sheet and roast for 25 to 30 minutes, flipping halfway, until golden and tender.
02 - While potatoes roast, heat butter and olive oil in a large skillet over medium-low heat. Add sliced onions and salt, cooking and stirring frequently until softened, about 10 minutes. Sprinkle sugar and thyme, then continue cooking, stirring occasionally, until deeply golden and caramelized, about 20 to 25 minutes. Lower heat if onions brown too quickly.
03 - Remove potatoes from the oven and arrange them in a shallow ovenproof baking dish or skillet, slightly overlapping the slices.
04 - Spread caramelized onions evenly over the layered potatoes. Sprinkle grated Gruyère cheese on top.
05 - Place the assembled dish back in the oven and bake for 10 to 12 minutes until the cheese is melted and bubbling. Broil for 2 to 3 minutes if an extra browned crust is desired.
06 - Garnish with chopped fresh parsley and serve immediately while hot.

# Expert Advice:

01 -
  • You get all the rich, caramelized onion and melted cheese magic without needing a spoon and bowl.
  • It's the kind of side dish that steals the show, leaving people wondering why they don't make it every week.
  • The crispy potato edges meet the soft, jammy onion interior in a way that feels like you've done something genuinely impressive.
02 -
  • Don't skip flipping the potatoes halfway through roasting—flat bottoms brown beautifully, but uneven cooking leaves some pale and others overdone.
  • The onions must be thinly sliced and cooked low and slow, or they'll never reach that jammy, sweet stage and you'll just have regular softened onions with brown bits.
  • Make sure your baking dish or skillet is ovenproof before you fill it; nothing ruins this faster than realizing your handle isn't oven-safe at the last moment.
03 -
  • Use a mandoline to slice potatoes uniformly, but watch your fingers—or just take your time with a sharp knife and accept that rustic thickness variations actually add charm.
  • If your onions are browning too quickly, add a splash of water or broth to slow the process and prevent bitterness from creeping in.
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