French Onion Frittata Recipe

Why You’ll Love This Recipe

This French Onion Frittata is the perfect blend of savory flavors and textures. The sweet, caramelized onions provide a deep, rich flavor that pairs perfectly with the crispy toasted bread and creamy eggs. The addition of Gruyère cheese adds a touch of nuttiness, while the fresh chives give it a burst of color and freshness. Whether you’re looking for a comforting brunch option or an easy weeknight dinner, this frittata has you covered. It’s easy to make, incredibly flavorful, and sure to impress anyone at your table.

Ingredients

• 2 tablespoons unsalted butter, divided

• 2 cups diced day-old bread

• 1 tablespoon olive oil

• 2 large yellow onions, thinly sliced

• 1 1/2 teaspoons kosher salt, divided

• 1 tablespoon balsamic vinegar

• 8 large eggs

• 1/4 cup whole or 2% milk

• 1 tablespoon Dijon mustard

• 1/4 teaspoon freshly ground black pepper

• 1/2 cup diced Gruyère cheese (2 ounces)

• 1 tablespoon finely chopped fresh chives

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

Directions

1. Arrange a rack in the middle of the oven and heat to 400°F.

2. Heat 1 tablespoon of the butter in a 10-inch cast iron skillet over medium heat until bubbling. Add the bread cubes to the pan, toss to coat with the butter, and arrange in a single layer. Toast the bread, tossing every minute or so, until golden-brown on all sides, about 5 minutes. Transfer the croutons to a bowl and set aside.

3. Reduce the heat to low. Add the olive oil, onions, and 1/2 teaspoon of salt to the same skillet. Cook, stirring every 5 to 10 minutes and scraping any browned bits from the bottom of the pan, until the onions are soft and deeply browned, about 40 minutes. Add the balsamic vinegar and scrape up any remaining browned bits.

4. In a large bowl, whisk together the eggs, milk, Dijon mustard, remaining 1 teaspoon salt, and black pepper. Stir the remaining tablespoon of butter and the croutons into the skillet with the onions, then spread into an even layer. Pour the egg mixture over the top and tilt the pan to ensure the eggs settle evenly. Top with the Gruyère cheese.

5. Cook the frittata on the stove for 2 to 4 minutes, until the edges begin to set.

6. Transfer the skillet to the oven and bake for 8 to 10 minutes, until the eggs are set. To check, cut a small slit in the center; if raw eggs run into the cut, bake for a few more minutes. If the eggs are set, remove the frittata from the oven.

7. Let the frittata cool in the pan for 5 minutes, then top with fresh chives, slice into wedges, and serve warm.

Servings and Timing

• Servings: 6

• Prep Time: 15 minutes

• Cook Time: 55 minutes (40 minutes for caramelizing onions, 15 minutes for frittata cooking)

• Total Time: 1 hour 10 minutes

Variations

• Add Vegetables: You can add other vegetables like spinach, bell peppers, or mushrooms for added flavor and nutrition.

• Use Different Cheeses: Swap out Gruyère for other cheeses like cheddar, mozzarella, or Swiss, depending on your preferences.

• Herbs: Try adding fresh thyme, rosemary, or parsley to the frittata for a different herbal twist.

• Gluten-Free Option: Substitute the day-old bread with gluten-free bread for a gluten-free version of this dish.

Storage/Reheating

• Storage: Store any leftover frittata in an airtight container in the refrigerator for up to 3 days.

• Reheating: To reheat, warm individual slices in the microwave for 30-60 seconds or heat in a skillet over medium heat until warmed through. You can also reheat the entire frittata in the oven at 350°F for 10-15 minutes.

FAQs

1. How do I know when the frittata is done baking?

Check by cutting a small slit in the center of the frittata. If raw eggs run into the cut, continue baking for a few more minutes. If the eggs are set, it’s ready.

2. Can I use a different type of bread for the frittata?

Yes! You can use any type of day-old bread, such as sourdough, whole wheat, or even gluten-free bread if needed.

3. Can I prepare the onions ahead of time?

Yes, you can caramelize the onions a day ahead and store them in the refrigerator. When you’re ready to make the frittata, simply heat them up before adding to the eggs.

4. Can I make this frittata dairy-free?

Yes, you can substitute the butter with a dairy-free alternative and use a plant-based milk like almond or oat milk. Use a dairy-free cheese substitute for the Gruyère.

5. Can I freeze the frittata?

While frittatas are best served fresh, you can freeze individual slices. Wrap each slice tightly in plastic wrap and store in an airtight container for up to 2 months. Reheat thoroughly before serving.

6. What other cheeses can I use instead of Gruyère?

You can substitute Gruyère with Swiss, cheddar, mozzarella, or any cheese that melts well.

7. Is this frittata suitable for vegetarians?

Yes, this frittata is vegetarian-friendly, as it contains no meat.

8. Can I make this recipe without a cast iron skillet?

If you don’t have a cast iron skillet, you can use any oven-safe skillet or baking dish. Just make sure it’s large enough to accommodate the ingredients.

9. Can I add meat to this frittata?

Yes, you can add cooked sausage or other cooked meats to the frittata for a non-vegetarian version.

10. How do I get the perfect golden-brown crust on the bread?

Make sure to toast the bread cubes on medium heat and toss them frequently to get a golden-brown color on all sides. Don’t rush this step; it adds texture and flavor to the frittata.

Conclusion

This French Onion Frittata is a deliciously savory and satisfying dish that combines the best flavors of a classic French onion soup with the convenience and ease of a frittata. Whether you’re looking to impress guests at brunch or need a simple yet flavorful meal, this frittata is a perfect choice. With its rich caramelized onions, crispy bread, creamy eggs, and melty cheese, it’s sure to become a family favorite. Enjoy it warm, topped with fresh chives, and serve it alongside your favorite salad or roasted vegetables for a complete meal.