# What You Need:
→ Potatoes
01 - 3.3 lbs Yukon Gold or russet potatoes, scrubbed and sliced ⅓ inch thick
02 - 2 tbsp olive oil
03 - ½ tsp kosher salt
04 - ¼ 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 - ½ tsp kosher salt
09 - 1 tsp fresh thyme leaves (or ½ 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:
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 - 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.
