This Spinach Casserole is loaded with melted cheese, tender mushrooms, and a lightly custardy bite from real eggs and not canned soup. It's the side dish I've made since my kids were small, back when getting them to eat a vegetable took a little cheese and a little strategy. Serve it next to a Chicken Roulade and it holds its own at a weeknight table or a holiday spread.
Spinach Casserole At A Glance
- 🕐 Total Time: 50 minutes (15 min prep + 35 min cook)
- 🍽️ Servings: 8
- 🍅 Cuisine Type: American comfort, cheesy casserole
- 🧅 Flavor Profile: Rich and sharp from melted cheddar, with garlicky depth from sautéed onion and mushrooms, mellowed by tender baked spinach
- 🥛 Dietary Info: Naturally gluten-free; contains dairy and eggs
- 📦 Storage Notes: Refrigerate in an airtight container for up to 4 days; freezes well whole or in slices for up to 2-3 months
- ⭐ Why You'll Love It: A kid-tested spinach side made with real ingredients, no canned soup in sight, cheesy enough that nobody notices they're eating a vegetable
Save And Summarize This Recipe
A lot of spinach casseroles lean on a can of condensed soup or a tub of cream cheese to do the work. This one doesn't. Real eggs and real cheese hold everything together, so what you get is a lightly custardy, deeply savory bake instead of something gummy or overly rich. If you're a fan of baked comfort sides, it's in the same family as a Noodle Casserole or Vegetable Casserole: simple, real ingredients, and the kind of dish that disappears fast at a holiday table.
Jump to:
Sautéing the onion and mushrooms before they go into the casserole is what keeps this from tasting watery or one-note. It gives the mushrooms a chance to brown and concentrate their flavor instead of steaming inside the bake. If mushrooms are your thing, you'll also want to try this Mushroom Cauliflower Skillet, which uses the same browning technique to build flavor. If you're building out a brunch or holiday spread, a Blintz Casserole pairs well alongside this one for a spread that covers both savory and sweet.
Key Ingredients
You will need the following ingredients to make this recipe for a spinach and mushroom recipe:
- Spinach - Frozen chopped spinach keeps this simple and consistent. Squeeze out as much water as you can before mixing it in, this is the step that keeps the casserole from turning watery. Fresh spinach works too; just wilt it in a pan first and give it the same squeeze. If you love cooking with spinach, the Spinach Lentil Soup is a heartier soup that uses spinach.
- Mushrooms - A brown button or baby portobello mushroom brings more flavor than the standard white variety, but any type works. Sauté until they start to brown before adding them to the mix, don't skip this step.
- Cheese - Cheddar is my go-to here for sharp, real flavor. Swap in mozzarella if you're serving picky eaters, or Swiss cheese if you want something a little different and with a sharper taste.
See the recipe card for quantities.
Do You Want to Save This Recipe?
Enter your email & I'll send it to your inbox. Plus, get great new recipes from me every week!
By submitting this form, you consent to receive emails from A Sweet Thyme
Variations
- Protein: Stir in shredded rotisserie chicken, cooked breakfast sausage, or crumbled bacon to turn this side into more of a main. This is the easiest way to stretch it for a bigger crowd.
- Herbs and seasonings: A pinch of crushed red pepper or fresh parsley on top adds some brightness without changing the base recipe.
- Vegetables: No mushrooms on hand? Bell peppers or finely chopped broccoli work in their place.
How To Make Spinach Casserole: Step-By-Step
Step 1: In a large skillet, sauté the onions in butter over medium heat until slightly cooked. Add in the fresh mushrooms. Cook the mushrooms until they start to brown. Set aside.
Step 2: Cook the frozen spinach in the microwave. Squeeze out the excess water and set aside.
Step 3: In a large bowl, add the spinach, cheese, egg, mushroom mixture, and spices. Mix well until everything is combined.
Step 4: Pour the spinach mixture into a greased casserole dish. Top the casserole with some extra cheese and bake it until the top is lightly browned about 35 minutes.
Let cool for 5 minutes before serving.
Recipe Tips:
Grease the dish well before adding the mixture. This casserole has enough cheese to make cleanup miserable if you skip this step, and it's the difference between clean slices and a fight with the pan.
Gwen's Pro Tip
Let it rest for 5 minutes before cutting into it. It firms up as it sits, and you'll get cleaner squares instead of a mushy first slice.
Spinach Casserole FAQ's
Yes. Wilt it in a pan first and squeeze out the excess water the same way you would with thawed frozen spinach.
More Side Dishes To Share
Let me know your thoughts on this Spinach Casserole by leaving a star rating below or by sharing it on Facebook, Instagram, Flipboard, or Pinterest!
Thank you!
Gwen
Spinach Casserole With Mushrooms
Do You Want to Save This Recipe?
Enter your email & I'll send it to your inbox. Plus, get great new recipes from me every week!
By submitting this form, you consent to receive emails from A Sweet Thyme
Equipment
Ingredients
- 2 frozen chopped spinach 10 oz bags
- 1 whole onion chopped
- 5 ounces mushrooms chopped
- 2 tablespoons butter
- 2 whole eggs
- 2 cups shredded cheese of choice
- 1 teaspoon salt
- ½ teaspoon pepper
- 2 teaspoon garlic powder
Instructions
- Preheat the oven to 375 degrees.
- Grease a 9x13 casserole dish and set aside.
- In a large skillet, saute the onions in butter over medium heat until soft and translucent.
- Add the mushrooms. Saute until the mushrooms are just starting to brown. Season with a touch of salt. Turn off the heat and set aside.
- Cook the spinach in the microwave according to the package. Drain the water out of the cooked spinach by squeezing the spinach in a colander over the sink.
- Place the spinach into a bowl.
- Add the onions and mushrooms to the bowl.
- Add the rest of the ingredients and combine.
- Pour the mixture into the greased casserole dish. Add more cheese if desired.
- Bake for 35 minutes to an hour. The top should look lightly brown and the cheese should be melted.
Gwen says
x
Anonymous says
X