# Ingredient List:
→ 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
# Steps:
01 - Preheat oven to 425°F and line a large baking sheet with parchment paper.
02 - Toss potato slices with olive oil, kosher salt, and black pepper. Arrange in a single layer on the prepared sheet and roast for 25 to 30 minutes, flipping once, until golden and tender.
03 - Meanwhile, heat butter and 1 tablespoon olive oil in a large skillet over medium-low heat. Add sliced onions and salt; cook, stirring often, for 25 to 30 minutes until deeply golden and caramelized. Stir in thyme and balsamic vinegar; cook 1 to 2 minutes more, then remove from heat.
04 - Lower oven temperature to 400°F in preparation for baking the assembled dish.
05 - Lightly grease a baking dish. Arrange roasted potato slices in slightly overlapping layers. Spread caramelized onions evenly over potatoes. Sprinkle Gruyère and optional Parmesan cheese on top.
06 - Bake the layered potatoes and onions for 10 to 15 minutes until cheese is melted and bubbling.
07 - Allow to cool slightly. Garnish with chopped parsley and serve warm.
