Onion Gratin

4.13 from 8 votes

My French style Onion Gratin bakes up in a cheesy sauce finished off with a crunchy herb crumb topping ~ it goes with everything!

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Prep Time:20

Cook Time:25

Total Time:45

Servings: 6 servings

Equipment

cast iron skillet or other oven ready skillet

Ingredients

2-3 large red onions
olive oil for brushing
2 Tbsp unsalted butter, divided
1 Tbsp all purpose flour
2/3 cups heavy cream
3 Tbsp dry sherry
salt and fresh cracked black pepper
dash of nutmeg, I grate mine fresh
handful of fresh thyme
1 cup shredded Gruyere cheese
2/3 cup breadcrumbs

Instructions

Preheat oven to 400F
Peel and thickly slice the onions about 1/2" thick. If you cut them much thicker than that, you may have trouble getting them cooked through.
Heat a grill pan until quite hot, and brush the onion slices lightly with olive oil. Grill the slices for a minute or two on each side so that they get slightly softened and have nice grill marks. Set them aside.
In a saucepan, heat 1 Tbsp of the butter over medium heat, and stir in the flour. Cook for a minute, stirring constantly. Pour in the cream and sherry and whisk until smooth. Stir constantly while the mixture comes up to a simmer and is thickened. Add salt and pepper to taste and the dash of nutmeg.
Pour the sauce into a cast iron skillet or gratin dish. Arrange the onion slices over the sauce.
Sprinkle the cheese evenly over all.
Stir the breadcrumbs together with the last tablespoon of melted butter, and a little salt, pepper, and a few thyme leaves. Sprinkle the breadcrumbs over the cheese,
Bake for about 20-25 minutes until browned and bubbling. Check the onions with the tip of a sharp knife, they should feel tender. You can run the gratin under the broiler at the last minute if you want extra browning,

Notes

*This recipe was first published in 2013, and was re-tested and rephotographed in 2024.

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Course: Side Dish

Cuisine: American, French

Author: Sue Moran

Keyword: cast iron skillet, French, onions, side dish

Nutrition

Calories: 287 kcal · Carbohydrates: 14 g · Protein: 9 g · Fat: 21 g · Saturated Fat: 13 g · Polyunsaturated Fat: 1 g · Monounsaturated Fat: 6 g · Trans Fat: 0.2 g · Cholesterol: 64 mg · Sodium: 254 mg · Potassium: 128 mg · Fiber: 1 g · Sugar: 3 g · Vitamin A: 715 IU · Vitamin C: 3 mg · Calcium: 272 mg · Iron: 1 mg

Nutritional information is provided as a courtesy and is an estimate only. This information comes from online calculators. Although The View from Great Island attempts to provide accurate nutritional information, these figures are only estimates.