Onions Au Gratin

Prep: 15 min Cook: 30 min Serves: 8 Cuisine: American

Onions Au Gratin offers tender, caramelized onions topped with a rich, cheesy sauce. The combination of Swiss and Parmesan cheeses creates a savory, golden crust perfect for cozy dinners or elegant gatherings. This comforting dish pairs well with roasted meats or as a standalone vegetarian delight.

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Ingredients

  • 6 medium yellow onions
  • 1/2 cup beef broth low salt
  • 2 tablespoons flour
  • 1/8 teaspoon pepper
  • 1/4 cup butter or margarine
  • 1/2 cup whipping cream
  • 1/2 cup Swiss cheese shredded
  • 1/2 cup grated Parmesan cheese

Instructions

  1. Slice the onions into 1/2-inch thick rings.
  2. Sauté the onions in butter until tender.
  3. Place the sautéed onions into a greased 8-inch square baking dish.
  4. In a bowl, stir the beef broth, whipping cream, flour, and pepper until smooth.
  5. Pour the mixture over the onions in the baking dish.
  6. Sprinkle the shredded Swiss cheese and grated Parmesan cheese over the top.
  7. Bake uncovered at 350°F for approximately 30 minutes or until the cheese is golden brown and the mixture is bubbly.

Tips & Substitutions

For a richer flavor, consider adding a splash of white wine to the broth mixture. If you're short on time, pre-sautéed frozen onions work, but fresh onions will provide better texture. You can also substitute the Swiss cheese with Gruyère for a more robust taste. For a gluten-free option, use cornstarch instead of flour.

Serving Suggestions

This dish makes a fantastic side for roasted meats or a hearty main alongside a green salad. It pairs beautifully with Beef Tenderloin With Roasted Shallots And Port or can be served as a comforting appetizer. For a complete meal, consider serving with a side of garlic bread or a fresh vegetable medley.

Storage & Reheating

Leftover Onions Au Gratin can be stored in an airtight container in the refrigerator for up to 3 days. To reheat, place in a preheated oven at 350°F for about 15-20 minutes until warmed through and the cheese is bubbly again. Avoid microwaving for best texture.

Nutrition & Diet Analysis (per serving)

Each serving of Onions Au Gratin contains roughly 255 calories, with 5g protein, 19g carbohydrates, and 18g fat. It is an excellent source of vitamin C (69% of the Daily Value), and a good source of dietary fiber. It also contributes 3g of dietary fiber toward your daily target.

255 kcal 13% DV
Protein Fat Carbs

Macronutrients

Protein 4.7g 9% DV
Total Fat 18.2g 23% DV
Carbs 19g 7% DV
Fiber 3.3g 12% DV
Sugar 1.8g 4% DV

Electrolytes

Sodium 94.4mg 4% DV
Potassium 264.5mg 6% DV
Cholesterol 48.4mg 16% DV

Vitamins & Minerals

Vitamin A 30.1mcg 3% DV
Vitamin C 62.5mg 69% DV
Vitamin D 0mcg
Calcium 49mg 4% DV
Iron 1.3mg 7% DV
Diet fit Low-carb Under 400 cal
Contains Milk Wheat/Gluten

Estimated from ingredients & per-serving nutrition — verify against package labels for allergies or strict diets.

* % Daily Values based on a 2,000 calorie diet (FDA 2020).

Frequently Asked Questions

Can I use other types of cheese in this recipe?

Yes, you can experiment with other cheeses such as cheddar or fontina. Each will bring a different flavor profile to the dish. Just keep in mind that some cheeses may melt differently, affecting the final texture.

What can I do if the onions are not tender after sautéing?

If the onions are still firm after sautéing, try cooking them a bit longer over medium heat, stirring frequently. You can also add a splash of beef broth to help them soften more quickly. The goal is to achieve a translucent and tender consistency before baking.

Is it possible to make this dish vegetarian?

Absolutely! Simply replace the beef broth with vegetable broth and use plant-based butter or margarine. This makes the dish suitable for vegetarians while still retaining a delicious flavor profile.

Nutrition is estimated from USDA FoodData Central ingredient data and may vary with brand, portion and preparation — see our methodology. This information is for general educational purposes only and is not medical or dietary advice (disclaimer).

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