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Caramelized Onion Scalloped Potatoes

Caramelized Onion Scalloped Potatoes

Thin-sliced potatoes bake in a creamy onion sauce with melty Gruyère and Parmesan. Comforting, golden, and irresistibly savory.
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Prep Time: 30 minutes
Cook Time: 1 hour 15 minutes
Total Time: 1 hour 45 minutes
Servings: 8

Ingredients
 

Main Ingredients

  • 2.25 lb Yukon Gold potatoes, thinly sliced Peeling optional
  • 1.5 lb yellow onions, thinly sliced
  • 3.5 tbsp unsalted butter for caramelizing onions
  • 1 tbsp olive oil
  • 2 tsp minced garlic
  • 1.25 tsp fresh thyme leaves, chopped
  • 2.5 tbsp all-purpose flour
  • 1.5 cup heavy cream
  • 1 cup whole milk
  • 0.5 cup low-sodium chicken broth or vegetable broth
  • 1 tsp Dijon mustard
  • 2.25 cup Gruyère cheese, shredded
  • 0.5 cup Parmesan cheese, finely grated
  • 1.5 tsp kosher salt divided
  • 1 tsp black pepper, freshly ground divided
  • 0.25 tsp ground nutmeg
  • 1 tbsp unsalted butter, for greasing for the baking dish
  • 2 tbsp chives, finely chopped for garnish

Instructions

Preparation Steps

  • Heat oven to 375°F. Butter a 9x13-inch baking dish.
  • Caramelize onions: Warm butter and oil in a large skillet over medium-low heat. Add onions and 1/2 tsp salt. Cook, stirring often, until deep golden, 25–30 minutes.
  • Stir in garlic and thyme; cook 1 minute until fragrant.
  • Make the sauce: Sprinkle flour over onions and stir 1 minute. Whisk in broth, milk, and cream until smooth. Add Dijon, nutmeg, 1 tsp salt, and 3/4 tsp pepper. Simmer 3–4 minutes to slightly thicken. Remove from heat.
  • Slice potatoes thinly if not done. Pat dry. Season with a pinch of salt and pepper.
  • Layer half the potatoes in the dish, overlapping. Spoon half the onion cream over. Scatter one-third of the Gruyère and a little Parmesan.
  • Repeat with remaining potatoes, sauce, and most of the remaining cheeses. Finish with the last handful of Gruyère and all the Parmesan on top.
  • Cover tightly with foil and bake 45 minutes, until the potatoes are nearly tender.
  • Uncover and bake 20–30 minutes more, until bubbling and deeply golden. Rest 10–15 minutes. Sprinkle with chives and serve.

Notes

Swap Gruyère with sharp white cheddar for a bolder bite, or add crisp bacon between layers for a smoky twist. Leftovers reheat well: cover and warm at 350°F until hot, or microwave individual portions. For extra browning, broil 1–2 minutes at the end.
This recipe is an original creation inspired by classic Caramelized Onion Scalloped Potatoes flavors. All ingredient ratios and instructions are independently developed.