Name: French Onion Frittata – A Classic Twist on Easy Recipes for Dinner
Prep time: 10 min
Cook time: 40 min
Total time: 50 min
Ingredients: 2 tablespoons unsalted butter; 2 large yellow onions, thinly sliced; 1/2 teaspoon kosher salt, plus more as needed; 1/4 teaspoon freshly ground black pepper; 1/4 cup low-sodium chicken or vegetable broth; 8 large eggs; 1/4 cup whole milk; 1 tablespoon Dijon mustard; 1 cup shredded Gruyère cheese, divided; Chopped fresh thyme leaves, for garnish (optional)

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This French Onion Frittata is the ultimate comfort food that combines the richness of caramelized onions with fluffy eggs and gooey cheese. Perfect for easy recipes for dinner, this dish also fits into your rotation of quick and easy recipes, vegetarian easy recipes, sweet easy recipes, easy meal recipes, air fryer easy recipes, and breakfast easy recipes.

1) Key Takeaways
2) Easy French Onion Frittata Recipe
3) Ingredients for French Onion Frittata
4) How to Make French Onion Frittata
5) Tips for Making French Onion Frittata
6) Making French Onion Frittata Ahead of Time
7) Storing Leftover French Onion Frittata
8) Try these Breakfast recipes next!
9) French Onion Frittata Recipe
10) Nutrition

1) Key Takeaways

This recipe is perfect for quick weeknight meals or a weekend brunch.
Made with simple pantry ingredients you probably already have.
A wonderful way to repurpose onions and eggs into a gourmet meal.
High in protein and naturally gluten-free, ideal for varied diets.

2) Easy French Onion Frittata Recipe

At Elena Cooks, we believe in creating comfort food with a gourmet twist—and this French Onion Frittata is exactly that. This dish brings all the depth and richness of French onion soup, including slowly caramelized onions and a blanket of melted cheese, into the simplicity of a frittata. Whether you’re whipping it up for a lazy weekend breakfast or adding it to your rotation of easy recipes for dinner, this frittata checks all the boxes: hearty, satisfying, and unfussy. From the first bite, you’ll love how the savory sweetness of golden onions mingles with rich eggs and sharp cheese, making each mouthful better than the last. And did I mention this is also a wonderful dish for those following a gluten-free lifestyle? With fewer than 10 ingredients and just one skillet, it’s the epitome of quick and easy recipes—and ideal for those moments when you need something truly delicious without the fuss.

3) Ingredients for French Onion Frittata

Unsalted Butter: Butter is the foundational fat for caramelizing onions, and unsalted allows you to control the seasoning throughout the cooking process. Make sure it’s fully melted and slightly foamy before adding the onions, as this will yield the best browning.

Yellow Onions: Yellow onions are ideal for caramelizing due to their natural sugars. Slice them thinly and cook low and slow to draw out the most flavor, which gives the frittata its signature sweet-savory base.

Kosher Salt & Black Pepper: Seasoning is essential for balancing the richness of the eggs and the sweetness of the onions. Use kosher salt for better absorption and fresh ground pepper for a bit of warmth and complexity.

Chicken or Vegetable Broth: A splash of broth deglazes the pan, lifting all that oniony goodness stuck to the bottom of the skillet, enhancing the overall depth of the dish while keeping it moist and flavorful.

Large Eggs: The heart of any frittata, eggs create a fluffy, protein-rich structure. Use fresh, organic eggs if possible for a better rise and deeper flavor in your finished frittata.

Whole Milk: Whole milk adds richness and a silky texture to the egg base. You could substitute with cream for an even more indulgent result, but whole milk strikes a perfect balance.

Dijon Mustard: A touch of Dijon cuts through the richness and adds a subtle zing that enhances the savory flavor profile. It’s a secret ingredient that makes the flavor more complex and irresistible.

Gruyère Cheese: Gruyère melts beautifully and has a nutty, slightly sweet taste that complements caramelized onions perfectly. If you can’t find Gruyère, Swiss cheese is a decent substitute.

Fresh Thyme: Optional but highly recommended, fresh thyme adds an herbaceous note that rounds out the flavors. Sprinkle it over the finished frittata for a fresh, fragrant touch.

4) How to Make French Onion Frittata

Step 1. Preheat your oven to 400°F and place an oven-safe skillet on the stove over medium heat. Add butter and once melted, toss in your sliced onions with salt and pepper. Stir occasionally and let them caramelize for about 25 minutes until they turn deep golden brown and soft. This step develops the bold flavor that defines this dish.

Step 2. Once the onions are caramelized, pour in your broth and allow it to simmer for 1–2 minutes. This not only deglazes the pan but also adds a final layer of savory depth. It’s a small step, but it makes a big difference in building that signature easy recipes for dinner taste.

Step 3. In a mixing bowl, whisk together the eggs, whole milk, Dijon mustard, and half of the shredded cheese until smooth. The Dijon in this step helps brighten the flavors of the otherwise rich egg base. Stir thoroughly to combine all the elements into one creamy mixture.

Step 4. Pour the egg mixture into the skillet with the onions. Gently stir to ensure the onions are evenly distributed throughout the eggs. Top it with the remaining cheese and transfer the skillet to the preheated oven.

Step 5. Bake for 15 to 18 minutes or until the eggs are fully set and the top is golden and slightly puffed. Remove from the oven and allow the frittata to cool for 5 minutes before slicing. Garnish with thyme for a fresh contrast to the rich interior.

5) Tips for Making French Onion Frittata

When it comes to making a frittata that wows, patience and quality ingredients go a long way. For starters, don’t rush the onion caramelization process. It might take up to 30 minutes, but that slow transformation of the onions is crucial for that iconic French onion flavor. If you’re short on time, prep them in advance and store in the fridge. For a slightly lighter version, you can substitute some of the whole eggs with egg whites or use low-fat milk, though full-fat options deliver the creamiest texture. And don’t skimp on the cheese—it helps develop that perfect crust on top! If you love vegetarian easy recipes or are exploring more easy meal recipes, this dish fits right into your kitchen routine. Make sure your skillet is oven-safe to prevent any mishaps when transitioning from stovetop to oven.

6) Making French Onion Frittata Ahead of Time

One of the best things about this dish is how well it holds up for later. This makes it one of our favorite air fryer easy recipes (yes, you can reheat slices in the air fryer for a quick crisp-up!). Simply prepare the frittata as directed, let it cool, and store it whole or sliced in an airtight container. For busy mornings or weeknight dinners, you can slice and reheat individual portions. To prevent dryness, add a splash of broth or milk before reheating in the oven or microwave. You can also enjoy it at room temperature, making it ideal for brunches or buffets. Whether you’re meal prepping or just like having flavorful options ready to go, this frittata delivers on every front.

7) Storing Leftover French Onion Frittata

To store leftovers, allow the frittata to cool completely before sealing it in an airtight container. It will keep in the refrigerator for up to 4 days. If you’re reheating in a microwave, cover with a damp paper towel to retain moisture. For the best texture, reheat in a preheated oven at 325°F for about 10 minutes or in an air fryer at 350°F for 5–6 minutes. This dish also freezes well: wrap individual slices in plastic wrap and store in a freezer-safe bag. To reheat, thaw overnight and warm through in the oven. Whether for breakfast, lunch, or easy recipes for dinner, it’s great to have on hand.

8) Try these Breakfast recipes next!

9) French Onion Frittata Recipe