Caramelized Onion Frittata
Elevate your breakfast, brunch, or light dinner with this irresistible Caramelized Onion Frittata—a dish that’s as elegant as it is comforting. Made with slow-cooked golden onions sautéed to perfection in a blend of olive oil and butter, this oven-baked frittata is infused with savory Parmesan cheese, a hint of fresh thyme, and a fluffy egg mixture. The result is a rich and flavorful casserole-style dish with a creamy center and subtly sweet, caramelized notes. Ready in under an hour and served straight from a cast iron skillet, this frittata is ideal for entertaining or meal prep, as it can be enjoyed warm or at room temperature. Whether you're looking for a protein-packed start to your day or a quick weeknight dinner, this recipe is a satisfying and wholesome choice.
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Recipe Information
Ingredients
- 2 tablespoons Olive oil
- 1 tablespoon Unsalted butter
- 2 large Yellow onions
- 0.5 teaspoons Salt
- 0.25 teaspoons Ground black pepper
- 8 pieces Large eggs
- 0.25 cups Whole milk
- 0.5 cups Parmesan cheese (grated)
- 1 teaspoon Fresh thyme leaves (optional)
Instructions
Peel and thinly slice the yellow onions.
In a large oven-safe skillet (preferably cast iron), heat the olive oil and butter over medium heat until melted and shimmering.
Add the sliced onions to the skillet and sprinkle with 1/4 teaspoon of salt. Stir to coat the onions in the oil and butter mixture.
Reduce the heat to low and cook the onions, stirring occasionally, for 25-30 minutes until caramelized and golden brown. If the onions begin to stick or brown too quickly, add a splash of water and continue cooking.
While the onions are caramelizing, preheat your oven to 375°F (190°C).
In a medium mixing bowl, whisk together the eggs, whole milk, remaining 1/4 teaspoon of salt, ground black pepper, Parmesan cheese, and fresh thyme if using. Set aside.
Once the onions are fully caramelized, spread them evenly across the skillet.
Pour the egg mixture over the onions, tilting the skillet gently to ensure the eggs spread evenly. Avoid stirring at this stage.
Cook the frittata on the stovetop over medium-low heat for 5-7 minutes, just until the edges begin to set. The center will still be slightly runny.
Transfer the skillet to the preheated oven and bake for 10-12 minutes, or until the frittata is puffed and the center is set.
Remove the skillet from the oven and let the frittata cool for 5 minutes before slicing.
Serve warm or at room temperature, and enjoy!
Nutrition Facts
Calories |
390 | ||
|---|---|---|---|
% Daily Value* |
|||
| Total Fat | 28.4 g | 36% | |
| Saturated Fat | 11.8 g | 59% | |
| Polyunsaturated Fat | 0.0 g | ||
| Cholesterol | 397 mg | 132% | |
| Sodium | 845 mg | 37% | |
| Total Carbohydrate | 10.2 g | 4% | |
| Dietary Fiber | 1.4 g | 5% | |
| Total Sugars | 5.1 g | ||
| Protein | 24.7 g | 49% | |
| Vitamin D | 2.5 mcg | 13% | |
| Calcium | 415 mg | 32% | |
| Iron | 2.1 mg | 12% | |
| Potassium | 289 mg | 6% | |
*The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
