A frittata is a versatile dish that’s perfect for breakfast, lunch, or dinner. Its simplicity and adaptability make it a go-to recipe for using up ingredients and creating a nutritious, satisfying meal. Whether served warm or at room temperature, a frittata is always a crowd-pleaser.

Ingredients Overview
Each ingredient in this frittata contributes to its delicious flavor and texture. The Muenster cheese adds a creamy, melty richness that pairs beautifully with the spinach. Frozen spinach, once thawed and drained, brings a hearty, earthy flavor that complements the sweet caramelized onions. Eggs provide the protein-rich base, while a touch of salt and pepper enhances the overall taste. For variations, fresh spinach can replace frozen, and you can experiment with cheeses like cheddar, Gruyère, or feta for different flavor profiles.
Step-by-Step Preparation
Start by preparing the ingredients. Thaw the frozen spinach completely, then drain and squeeze out all excess moisture. This step is crucial to avoid adding unnecessary water to the frittata, which could affect its texture. Chop the onion evenly to ensure it cooks uniformly and adds a sweet, caramelized flavor to every bite.
In a large skillet, heat the vegetable oil over medium-high heat. Add the chopped onion and sauté, stirring occasionally, until softened and slightly golden, about 3 minutes. Stir in the spinach and continue cooking until any remaining moisture evaporates. This ensures the frittata will have a firm and fluffy texture.
In a large mixing bowl, whisk together the eggs, salt, and pepper until the mixture is smooth and well-seasoned. Add the sautéed spinach-onion mixture and the shredded Muenster cheese, gently folding them together until evenly combined.
Pour the mixture into a lightly greased 9-inch pie pan, spreading it out evenly. Place the pan in a preheated oven at 350°F (175°C) and bake for about 30 minutes, or until the frittata is golden on top, slightly puffed, and the eggs are fully set.
Once out of the oven, allow the frittata to rest for about 10 minutes before slicing. This step helps it firm up for easier serving.

Recipe Tips & Frequently Asked Questions
Avoiding a Soggy Frittata:
Ensure the spinach is thoroughly drained, and avoid adding too many wet ingredients.
Cheese Variations:
Try using mozzarella for a milder flavor or feta for a tangy twist.
Even Cooking:
Preheating the oven and using a properly greased pan will ensure consistent results.
Can I use fresh spinach instead of frozen?
Yes, just sauté the fresh spinach until wilted and remove excess liquid before adding it to the mixture.
How do I make this recipe dairy-free?
Use a plant-based cheese alternative or simply skip the cheese and add more vegetables for flavor.
What’s the best way to ensure the frittata doesn’t stick to the pan?
Grease the pan generously with oil or butter and use a non-stick or well-seasoned pan.
What to Serve With This Recipe
Pair this frittata with a fresh green salad dressed with a light vinaigrette or serve it alongside crusty bread or roasted potatoes. For a complete brunch spread, include fresh fruit, avocado slices, or a dollop of sour cream on the side.
Storage and Reheating Tips
Store any leftovers in an airtight container in the refrigerator for up to three days. Reheat individual slices in the microwave or oven for a few minutes to maintain the texture and flavor.
This frittata recipe is a versatile, foolproof dish that can be easily customized with your favorite vegetables, cheeses, and seasonings. Its simple preparation and satisfying flavors make it a fantastic addition to any meal. Experiment with ingredients and enjoy creating your own version of this classic recipe.

Ingredients
1 (10-ounce) package frozen chopped spinach, thawed, drained, and squeezed dry
1 medium onion, chopped
5 large eggs, beaten
3 cups shredded Muenster cheese
1 tablespoon vegetable oil
¼ teaspoon salt
⅛ teaspoon ground black pepper
Instructions
Gather all ingredients and preheat your oven to 350°F (175°C). Lightly grease a 9-inch pie pan to prepare it for baking.
Heat the vegetable oil in a large skillet over medium-high heat. Add the chopped onion and sauté, stirring occasionally, until softened, about 3 minutes. Incorporate the spinach and continue cooking until any excess moisture evaporates completely.
In a large mixing bowl, whisk together the beaten eggs, salt, and pepper. Add the shredded Muenster cheese and the spinach-onion mixture, stirring until the ingredients are thoroughly combined.
Pour the mixture into the prepared pie pan, spreading it evenly.
Bake in the preheated oven for approximately 30 minutes, or until the eggs are fully set and the frittata is golden and slightly puffed.
Remove from the oven and allow the frittata to cool for about 10 minutes before slicing and serving.
Serve warm and enjoy this flavorful dish!

Frittata Recipe
Ingredients
- 1 10-ounce package frozen chopped spinach, thawed, drained, and squeezed dry
- 1 medium onion chopped
- 5 large eggs beaten
- 3 cups shredded Muenster cheese
- 1 tablespoon vegetable oil
- ¼ teaspoon salt
- ⅛ teaspoon ground black pepper
Instructions
- Gather all ingredients and preheat your oven to 350°F (175°C). Lightly grease a 9-inch pie pan to prepare it for baking.
- Heat the vegetable oil in a large skillet over medium-high heat. Add the chopped onion and sauté, stirring occasionally, until softened, about 3 minutes. Incorporate the spinach and continue cooking until any excess moisture evaporates completely.
- In a large mixing bowl, whisk together the beaten eggs, salt, and pepper. Add the shredded Muenster cheese and the spinach-onion mixture, stirring until the ingredients are thoroughly combined.
- Pour the mixture into the prepared pie pan, spreading it evenly.
- Bake in the preheated oven for approximately 30 minutes, or until the eggs are fully set and the frittata is golden and slightly puffed.
- Remove from the oven and allow the frittata to cool for about 10 minutes before slicing and serving.
- Serve warm and enjoy this flavorful dish!