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cheesy scalloped potatoes with caramelized onions recipe
Ash Tyrrell

Cheesy Scalloped Potatoes with Caramelized Onions Recipe

The first time I made these cheesy scalloped potatoes with caramelized onions, I couldn’t believe how comforting and delicious they turned out. The creamy sauce, gooey cheese, and sweet onions came together like magic.
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Prep Time 30 minutes
Cook Time 2 hours 30 minutes
Servings: 8
Ingredients Method Notes

Ingredients
  

  • 2 tablespoons salted butter – For caramelizing the onions and adding richness.
  • 2 large yellow onions thinly sliced – Fresh onions work best; avoid pre-chopped.
  • 1/4 cup dry white wine – Deglazes the pan and deepens onion flavor. Sub with broth if you prefer.
  • 3 garlic cloves minced – Adds aromatic warmth.
  • 2 teaspoons fresh thyme chopped – Fresh herbs lift the richness of the dish.
  • 1 1/2 cups heavy cream – Gives the sauce its silky creaminess.
  • 1 cup whole milk – Balances the richness with a smoother texture.
  • 1/4 teaspoon cayenne pepper – A tiny kick of heat without overpowering.
  • 1 cup Gruyère cheese freshly grated – Always grate cheese fresh for the best melt.
  • 1 cup sharp cheddar cheese freshly grated – Perfect for a bold, cheesy topping.
  • 4 large russet or Yukon gold potatoes thinly sliced – Don’t use waxy potatoes; they won’t layer as well.

Method
 

  1. Melt butter in a large skillet over medium heat, then add sliced onions. Cook them slowly, stirring now and then, until they soften and turn golden—this takes about 10–12 minutes.
  2. Deglaze the pan with white wine, scraping up all the tasty bits. Stir in garlic, thyme, salt, and pepper, then cook for another 5 minutes. The onions should be sweet, rich, and caramelized beautifully.
  3. In a measuring cup, whisk together heavy cream, milk, cayenne, salt, and pepper. Stir in the Gruyère cheese and let it melt just slightly. This creamy base doesn’t need to be cooked on the stove—it will thicken in the oven and coat the potatoes perfectly.
  4. Using a mandoline, slice the potatoes thin and even. Generously butter the casserole dish, then pour a small amount of sauce on the bottom.
  5. Add a layer of potatoes, followed by caramelized onions and more sauce. Keep layering until everything is used, finishing with a creamy topping.
  6. Cover the dish with foil and bake at 350°F for 2 hours. This slow cooking allows the potatoes to soak in all the flavors. Remove the foil, sprinkle cheddar cheese over the top, and bake for another 20 minutes. The top should be bubbling and golden brown.
  7. Once baked, sprinkle fresh thyme or parsley over the top for a pop of freshness. Serve hot and enjoy the creamy, cheesy, caramelized goodness in every bite.

Notes

  • I always slice potatoes as thin as possible so they bake evenly.
  • I caramelize the onions slowly without rushing—it makes a huge difference.
  • I butter the casserole dish generously for both flavor and to prevent sticking.
  • I never skip the cheddar topping—it gives the dish that irresistible crust.