French Onion Soup Potatoes (Printable)

Roasted potato slices layered with caramelized onions and melted Gruyère cheese, inspired by classic French flavors.

# What You Need:

→ Potatoes

01 - 3.3 lbs Yukon Gold or russet potatoes, scrubbed and sliced 1/3 inch thick
02 - 2 tbsp olive oil
03 - 1/2 tsp kosher salt
04 - 1/4 tsp freshly ground black pepper

→ Caramelized Onions

05 - 3 large yellow onions, thinly sliced
06 - 2 tbsp unsalted butter
07 - 1 tbsp olive oil
08 - 1/2 tsp kosher salt
09 - 1 tsp fresh thyme leaves (or 1/2 tsp dried thyme)
10 - 1 tsp balsamic vinegar

→ Topping

11 - 7 oz Gruyère cheese, grated
12 - 1 oz Parmesan cheese, grated (optional)
13 - 2 tbsp chopped fresh parsley (for garnish)

# How To Make It:

01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper.
02 - Toss potato slices with olive oil, salt, and pepper. Arrange in a single layer on the prepared sheet. Roast for 25-30 minutes, flipping once, until golden and tender.
03 - While potatoes roast, heat butter and 1 tbsp oil in a large skillet over medium-low heat. Add onions and salt; cook, stirring often, for 25-30 minutes until deeply golden and caramelized. Stir in thyme and balsamic vinegar; cook 1-2 minutes more. Remove from heat.
04 - Reduce oven temperature to 400°F.
05 - Arrange roasted potato slices in a lightly greased baking dish, slightly overlapping. Spoon caramelized onions evenly over the potatoes. Sprinkle Gruyère (and Parmesan, if using) over the top.
06 - Bake for 10-15 minutes until cheese is melted and bubbling.
07 - Let cool slightly. Garnish with chopped parsley and serve warm.

# Expert Hints:

01 -
  • It delivers all the caramelized onion and melted cheese magic of French onion soup without the broth or the bowls.
  • The potatoes get crispy on the edges and creamy in the middle, soaking up all that sweet onion flavor.
  • You can prep the onions ahead and assemble everything in minutes when you're ready to bake.
  • It works as a side dish or a full vegetarian meal with a simple salad on the side.
02 -
  • Don't rush the onions; if they start to brown too fast, lower the heat and add a splash of water to slow things down and keep them from burning.
  • Slice the potatoes evenly, about a third of an inch thick, so they all cook at the same rate and you don't end up with some that are raw and others that are mushy.
  • If your baking dish is small, layer the potatoes and onions in two or three layers instead of one, and add a bit more cheese between the layers.
03 -
  • Use a mandoline to slice the potatoes evenly and quickly, but watch your fingers; I've nicked myself more times than I care to admit.
  • Let the dish rest for five minutes after baking so the cheese sets slightly and you can serve it without everything sliding apart.
  • If the cheese isn't browning enough, switch the oven to broil for the last two minutes, but stay close because it can go from golden to burnt in seconds.
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