Spinach, Pepper & Feta Baked Egg Casserole
The dish in your photo appears to be a crustless vegetable-and-cheese baked egg casserole/frittata with spinach, red bell pepper, mushrooms or olives, and melted cheese. It is similar to a deep-dish frittata and is excellent for breakfast, brunch, lunch, or meal prep.
Since the image doesn’t contain the original written recipe, the quantities below are a reconstructed recipe designed to produce a similar appearance and texture.
Recipe at a Glance
Yield: 6–8 servings
Prep: 20 minutes
Bake: 35–45 minutes
Total: About 1 hour
Pan: 9-inch / 23-cm round deep baking dish
Oven: 350°F (175°C)
Texture: Firm around the edges, soft and creamy in the center
Cuisine style: Mediterranean-inspired
Diet: Vegetarian, naturally crustless
Nuts: No nuts in the basic recipe
FULL INGREDIENT LIST
Eggs & dairy
10 large eggs
½ cup (120 ml) whole milk
½ cup (120 g) sour cream or plain Greek yogurt
1 cup (100–120 g) shredded mozzarella
½ cup (50 g) crumbled feta
¼ cup (25 g) grated Parmesan, optional
Vegetables
3 cups (about 90 g) fresh spinach, roughly chopped
1 medium red bell pepper, diced
1 cup (150 g) mushrooms, finely sliced
½ medium red onion, finely diced
2 cloves garlic, minced
¼ cup (35–40 g) chopped Kalamata olives, optional
Seasoning
1 teaspoon dried oregano
½ teaspoon dried basil
½ teaspoon salt
½ teaspoon black pepper
¼ teaspoon red pepper flakes, optional
Cooking
1½ tablespoons olive oil
Butter or additional oil for greasing the dish
Optional garnish
1 tablespoon fresh parsley
1 tablespoon fresh dill
A little extra feta
Freshly ground black pepper
STEP-BY-STEP RECIPE
1. Prepare the baking dish
Preheat your oven to:
350°F / 175°C
Lightly grease a 9-inch deep round baking dish with butter or olive oil.
A glass or ceramic dish works particularly well.
2. Prepare the vegetables
Heat 1 tablespoon olive oil in a large skillet over medium heat.
Add the diced onion and bell pepper.
Cook for approximately 3–4 minutes, stirring occasionally.
Add the mushrooms.
Cook another 4–5 minutes, until the mushrooms have released most of their moisture.
Add the minced garlic and cook for approximately 30 seconds.
3. Add the spinach
Add the chopped spinach in handfuls.
Cook for 1–2 minutes, just until wilted.
Important
Transfer the vegetables to a plate and allow them to cool slightly.
If the spinach mixture looks wet, press it gently with paper towels or drain it in a colander.
Removing excess water is one of the most important steps.
Too much moisture can make the finished casserole watery.
4. Make the egg mixture
Crack the 10 eggs into a large mixing bowl.
Whisk until the yolks and whites are completely combined.
Add:
milk
sour cream or Greek yogurt
salt
pepper
oregano
basil
red pepper flakes
Whisk until smooth.
5. Add the cheese
Stir into the egg mixture:
mozzarella
feta
Parmesan, if using
Reserve a small amount of mozzarella and feta for the top.
🫑 6. Combine everything
Add the cooled vegetables to the egg mixture.
Stir gently until the spinach, peppers, mushrooms and onions are evenly distributed.
If using Kalamata olives, fold them in now.
7. Fill the baking dish
Pour the mixture into your greased baking dish.
Spread the vegetables evenly.
Sprinkle the reserved cheese over the top.
For the appearance in your photograph, arrange a few pieces of:
spinach
red pepper
feta
on the surface.
8. Bake
Place the dish in the center of the oven.
Bake at 350°F (175°C) for approximately 35–45 minutes.
Start checking around 35 minutes.
The casserole is finished when:
the edges are golden
the top is lightly browned
the center is mostly set
the eggs no longer look liquid
a knife inserted near the center comes out mostly clean
The center may have a very slight wobble when you remove it. It will continue cooking as it rests.
9. Rest before cutting
Remove from the oven and allow it to rest for 10–15 minutes.
This lets the eggs finish setting and makes much cleaner slices.
Garnish with fresh parsley or dill.
HOW TO SERVE
Cut into 6–8 wedges.
Serve warm with:
avocado
tomato salad
fresh fruit
roasted potatoes
toasted bread
green salad
Greek yogurt
salsa
For breakfast, it’s especially good with toast and fresh tomatoes.
HOW TO GET THE TEXTURE IN THE PHOTO
The casserole shown has a fairly firm, sliceable texture rather than a wet scrambled-egg consistency.
Three things matter most:
1. Don’t add too much milk
For 10 eggs, ½ cup milk is plenty.
2. Remove water from vegetables
Spinach and mushrooms contain lots of water.
Cook them first and drain thoroughly.
3. Don’t overbake
Overbaking produces rubbery eggs.
Take it out when the center is just set.
CHEESE OPTIONS
You don’t have to use exactly the cheeses above.
Creamy Mediterranean
Feta
Mozzarella
Richer
Cheddar
Gruyère
Mild
Monterey Jack
Mozzarella
Stronger flavor
Feta
Parmesan
sharp cheddar
For the closest appearance to the photograph, mozzarella + feta + Parmesan works very well.
VEGETABLE VARIATIONS
You can easily change the vegetables.
Spinach & mushroom
Use:
spinach
mushrooms
onion
garlic
Broccoli & cheddar
Replace mushrooms and peppers with:
1½ cups cooked chopped broccoli
cheddar cheese
Mediterranean
Use:
spinach
roasted red pepper
feta
Kalamata olives
sun-dried tomatoes
Zucchini
Add 1 cup grated zucchini, but squeeze out as much water as possible before adding.
Asparagus
Use 1 cup chopped, lightly cooked asparagus.
PROTEIN ADDITIONS
If you don’t need it vegetarian, you can add:
cooked bacon
diced ham
cooked sausage
shredded chicken
smoked salmon
Use approximately 1 cup cooked protein.
Make sure meat is fully cooked before adding it.
SPICY VERSION
For a little heat, add:
½ teaspoon red pepper flakes
1 finely diced jalapeño
½ teaspoon smoked paprika
Pepper Jack cheese also works beautifully.
DAIRY-FREE VERSION
Replace the dairy with:
unsweetened plant milk
dairy-free shredded cheese
dairy-free feta alternative
Use an unsweetened plant milk rather than vanilla or sweetened varieties.
GLUTEN-FREE
The basic recipe is naturally crustless and gluten-free, provided your individual cheese and other packaged ingredients are gluten-free.
No flour or breadcrumbs are required.
ALLERGEN & NUT INFORMATION
Basic recipe contains:
Eggs
Milk/dairy
Does not normally contain:
Peanuts
Tree nuts
Wheat/gluten
Soy
However, packaged cheese and other ingredients can have cross-contact warnings, so check labels if cooking for someone with a severe allergy.
Nut-free version
The recipe is already nut-free if you use plain dairy products and don’t add nuts.
Want extra crunch?
You can sprinkle toasted walnuts, almonds, or pine nuts on individual servings, but this is optional and changes the dish’s allergen profile.
APPROXIMATE NUTRITION
Using 8 servings and the ingredients above:
Nutrient Approx. per serving
Calories 220–260 kcal
Protein 15–17 g
Carbohydrates 6–8 g
Fat 15–18 g
Saturated fat 6–8 g
Fiber 1–2 g
Sugars 2–3 g
Calcium 200–250 mg
Sodium 450–600 mg
These are estimates, not laboratory measurements. Sodium varies considerably depending on the feta, Parmesan, olives and added salt.
STORAGE & MEAL PREP
Refrigerator
Cool completely, cover and refrigerate.
Best quality for approximately 3–4 days.
Freezer
Cut into individual portions.
Wrap each piece tightly and freeze for up to approximately 2 months.
Thaw overnight in the refrigerator.
Reheat at:
350°F / 175°C for 10–15 minutes
or microwave individual pieces until heated through.
MAKE-AHEAD BREAKFAST
This recipe is excellent for meal prep.
Sunday preparation
Bake the entire casserole.
Cool completely.
Cut into 8 portions.
Refrigerate.
Reheat individual portions throughout the week.
You can also add a piece of toast and fruit for a complete breakfast.
RECIPE Q&A
Can I use frozen spinach?
Yes. Thaw it completely and squeeze out as much water as possible.
Use approximately 1 cup thawed, squeezed spinach instead of 3 cups fresh.
Why is my casserole watery?
Usually because the vegetables released too much moisture.
Spinach, mushrooms and zucchini should be cooked first and drained well.
Why did my eggs become rubbery?
They were probably overbaked or baked at too high a temperature.
Remove the casserole as soon as the center is set.
Can I skip the sour cream?
Yes.
Replace it with an additional ½ cup milk or Greek yogurt, although Greek yogurt gives a creamier result.
Can I make it without cheese?
Yes, but cheese contributes both flavor and moisture/fat. If omitting it, consider adding another vegetable and a little extra seasoning.
Can I use egg whites?
Yes, but an all-egg-white casserole will be leaner and somewhat less rich.
For better texture, use a mixture of whole eggs and egg whites.
Can I use a rectangular pan?
Absolutely.
An approximately 8 × 8-inch baking dish works well.
A shallower pan will usually cook faster, so begin checking earlier.
Can I make this in a muffin pan?
Yes.
Divide the mixture among greased muffin cups and bake at 350°F/175°C for roughly 18–25 minutes.
They’re excellent for grab-and-go breakfasts.
Can I add potatoes?
Yes. Use approximately 1 cup cooked diced potatoes.
Don’t add raw potatoes because they may remain undercooked by the time the eggs are done.
Can I add tomatoes?
Yes, but use them sparingly.
Fresh tomatoes contain lots of water. Remove the seeds and excess liquid, or use sun-dried tomatoes.
Is this a frittata?
It’s very similar.
A traditional frittata is usually cooked partly on the stovetop and finished in the oven, whereas this version is designed as a fully baked casserole.
Can I eat it cold?
Yes. It’s perfectly good cold or at room temperature and makes a convenient lunch.
How do I make the top more golden?
Sprinkle a little extra mozzarella and Parmesan over the top during the last few minutes of baking, or briefly use the broiler/grill at the end.
Watch it closely because cheese can burn quickly.
Best Version for the Photo
For the closest result to the pictured casserole, I’d use:
10 eggs + ½ cup milk + ½ cup Greek yogurt + spinach + red bell pepper + mushrooms + red onion + garlic + feta + mozzarella + Parmesan + oregano.
Cook the vegetables first, remove as much moisture as possible, then bake the egg mixture in a deep glass dish at 350°F/175°C for about 40 minutes.
