Spinach and Tomato Baked Frittata

Imperial May 13, 2026May 13, 2026

Quick Recipe Version (TL;DR)

Yield: 6 servings
Prep Time: 15 minutes
Cook Time: 28 minutes
Total Time: 43 minutes

Quick Ingredients

1 tablespoon extra-virgin olive oil
1 small yellow onion, finely diced, about 1 cup
2 garlic cloves, minced
5 ounces baby spinach, roughly chopped if large
1 cup cherry or grape tomatoes, halved, about 6 ounces
8 large eggs
1/3 cup whole milk or half-and-half
3/4 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
1/4 teaspoon dried oregano
1/2 cup shredded sharp cheddar, mozzarella, or Monterey Jack cheese, about 2 ounces
1/3 cup crumbled feta cheese, about 1 1/2 ounces
1 tablespoon chopped fresh basil or parsley, optional, for serving

Do This

1. Heat the oven to 375°F and place a rack in the center.
2. In a 10-inch oven-safe skillet, sauté the onion in olive oil for 5 minutes, then add garlic for 30 seconds.
3. Add spinach and cook for 2 to 3 minutes, until wilted and excess moisture has mostly evaporated.
4. Whisk eggs, milk, salt, pepper, and oregano in a bowl; stir in most of the cheese.
5. Scatter tomatoes in the skillet, pour in the egg mixture, and top with remaining cheese.
6. Bake for 15 to 18 minutes, until the center is just set and the internal temperature reaches 160°F.
7. Rest for 5 to 10 minutes, garnish with herbs if using, then slice into wedges and serve warm or at room temperature.

Why You’ll Love This Recipe

Easy but elegant: It looks like a brunch centerpiece, but the method is simple enough for a weekday.
Great hot or at room temperature: Slice it like a pie for breakfast, brunch, lunchboxes, or a light dinner.
Vegetable-packed: Tender spinach, sweet tomatoes, and savory onions make every bite colorful and satisfying.
Make-ahead friendly: Bake it once, then enjoy slices for several days with toast, salad, or roasted potatoes.

Grocery List

Produce: 1 small yellow onion, 2 garlic cloves, 5 ounces baby spinach, 1 cup cherry or grape tomatoes, fresh basil or parsley if desired
Dairy: 8 large eggs, 1/3 cup whole milk or half-and-half, 1/2 cup shredded sharp cheddar, mozzarella, or Monterey Jack cheese, 1/3 cup crumbled feta cheese
Pantry: Extra-virgin olive oil, kosher salt, black pepper, dried oregano

Full Ingredients

Vegetables

1 tablespoon extra-virgin olive oil
1 small yellow onion, finely diced, about 1 cup
2 garlic cloves, minced
5 ounces baby spinach, roughly chopped if the leaves are large
1 cup cherry or grape tomatoes, halved, about 6 ounces

Egg Mixture

8 large eggs
1/3 cup whole milk or half-and-half
3/4 teaspoon kosher salt, or 1/2 teaspoon fine sea salt
1/4 teaspoon freshly ground black pepper
1/4 teaspoon dried oregano

Cheese and Finish

1/2 cup shredded sharp cheddar, mozzarella, or Monterey Jack cheese, about 2 ounces
1/3 cup crumbled feta cheese, about 1 1/2 ounces
1 tablespoon chopped fresh basil or parsley, optional, for serving

Step-by-Step Instructions

Step 1: Preheat the oven and prepare your pan

Place a rack in the center of the oven and preheat to 375°F. Use a 10-inch oven-safe skillet, such as cast iron or stainless steel. If your skillet is not naturally nonstick, make sure it is well-oiled so the frittata releases cleanly after baking.

Step 2: Whisk the egg base

In a medium bowl, whisk together 8 large eggs, 1/3 cup whole milk or half-and-half, 3/4 teaspoon kosher salt, 1/4 teaspoon black pepper, and 1/4 teaspoon dried oregano. Whisk until the eggs are evenly blended and no large streaks of egg white remain. Stir in about three-quarters of the shredded cheese and feta, saving the rest for the top.

Step 3: Sauté the onion

Set the oven-safe skillet over medium heat and add 1 tablespoon olive oil. When the oil shimmers, add the diced onion. Cook for 5 minutes, stirring occasionally, until the onion softens and turns lightly translucent. This gentle cooking step builds a sweet, savory base for the frittata.

Step 4: Add garlic and wilt the spinach

Add the minced garlic and cook for 30 seconds, stirring constantly so it becomes fragrant but does not brown. Add the spinach by the handful, stirring as it wilts. Cook for 2 to 3 minutes, until the spinach is fully wilted and most of the moisture in the pan has evaporated. If the skillet looks watery, cook for 1 additional minute before adding the eggs.

Step 5: Add tomatoes and pour in the eggs

Scatter the halved tomatoes evenly over the spinach and onion mixture. Give the egg mixture one more quick whisk, then pour it into the skillet. Use a spatula to gently nudge the vegetables around so they are evenly distributed, but do not overmix. Sprinkle the remaining shredded cheese and feta over the top.

Step 6: Bake until just set

Transfer the skillet to the preheated 375°F oven. Bake for 15 to 18 minutes, until the edges are puffed, the top looks set, and the center has only the slightest gentle wobble. For the most accurate doneness, the center should register 160°F on an instant-read thermometer. Avoid overbaking, which can make the eggs rubbery.

Step 7: Rest, slice, and serve

Let the frittata rest in the skillet for 5 to 10 minutes. This helps the eggs finish setting and makes clean slices easier. Run a thin spatula around the edge, then cut into 6 wedges, just like a pie. Garnish with chopped fresh basil or parsley if desired. Serve warm, at room temperature, or chilled for a make-ahead breakfast.

Pro Tips

Cook off extra moisture: Spinach and tomatoes can release water. Let the spinach moisture evaporate before adding eggs so the frittata bakes up tender, not soggy.
Use medium heat on the stovetop: High heat can brown the vegetables too quickly and toughen the eggs around the edges.
Do not overbake: Pull the frittata when the center is just set. It will continue to firm up as it rests.
Choose a flavorful cheese: Feta adds salty brightness, while cheddar, mozzarella, or Monterey Jack gives creamy melt and structure.
Let it rest before slicing: A short rest helps the wedges hold their shape and gives the flavors time to settle.

Variations

Mediterranean-style: Add 1/4 cup chopped Kalamata olives and replace the shredded cheese with extra feta. Finish with fresh dill or parsley.
Extra-protein version: Stir in 1/2 cup cooked diced ham, turkey sausage, or crumbled cooked bacon before pouring in the eggs.
Spicy tomato frittata: Add 1/4 teaspoon crushed red pepper flakes with the garlic and use pepper Jack cheese for a gentle kick.

Storage & Make-Ahead

Cool leftover frittata completely, then store slices in an airtight container in the refrigerator for up to 4 days. Reheat individual slices in the microwave for 30 to 60 seconds, or warm several slices in a 325°F oven for 10 to 12 minutes. The frittata may also be served at room temperature, but do not leave it out for more than 2 hours. To make it ahead, cook the onion, garlic, and spinach up to 2 days in advance and refrigerate; when ready to bake, warm the vegetables briefly in the skillet, add tomatoes and the egg mixture, and bake as directed. Fully baked slices can be frozen for up to 2 months; thaw overnight in the refrigerator before reheating.

Nutrition (per serving)