French Onion Potato Gratin

This French onion potato gratin is a tasty, cheesy potato dish featuring caramelized onions and a crisp crouton topping.

Preparation Details

Prep Time: 30 mins

Cook Time: 1 hr 30 mins

Total Time: 2 hrs 15 mins

Servings: 12

Ingredients

• 1 tablespoon butter, plus more for greasing
• 1 tablespoon olive oil
• 2 sweet onions, peeled and cut into thin wedges
• 3 cloves garlic, minced
• 1 1/4 teaspoons salt
• 1/2 teaspoon freshly ground black pepper
• 1 1/2 cups whipping cream
• 1/2 cup milk
• 1 tablespoon snipped fresh thyme
• 3 pounds yukon gold potatoes, thinly sliced
• 2 1/2 cups shredded Gruyere cheese, divided
• 1 cup French fried onions
• 2 cups garlic and herb croutons, coarsely crushed

Steps

1. Gather all ingredients.
2. Lightly grease a 3-quart rectangular or oval baking dish.
3. Heat butter and olive oil in a large skillet over medium heat. Stir in onion wedges. Cook, covered, until onions are tender, stirring occasionally, about 20 minutes. (If necessary, reduce heat to medium-low to prevent overbrowning before onions are tender.) Increase heat to medium-high and cook, uncovered, until onions are golden, stirring frequently, about 5 minutes more. Add garlic and cook 30 seconds more. Remove from heat and season with 1/4 teaspoon each salt and pepper. Set aside.
4. Preheat the oven to 350 degrees F (180 degrees C).
5. Stir together whipping cream, milk, thyme, remaining 1 teaspoon salt, and 1/4 teaspoon pepper; in a bowl; set aside.
6. Arrange half of the potatoes in the prepared dish, overlapping as necessary. Sprinkle with caramelized onions. Sprinkle with 1 cup Gruyere cheese. Layer remaining potatoes over cheese. Pour cream mixture over potatoes and top with 1 cup Gruyere cheese.
7. Bake in the preheated oven for 50 minutes.
8. Top with French friend onions, crushed croutons, and remaining 1/2 cup cheese. Bake until potatoes are tender and cheese is melted, 10 to 15 minutes more. Let stand for 15 minutes before serving.