Crustless Quiche with Spinach and Mushrooms

Crustless quiche is easy to make, keeps well, and can be reheated all week. In this vegetarian crustless quiche recipe, I used spinach and sliced mushrooms, but it’s so easy to adapt. Use what you have on hand and serve low-carb, gluten-free crustless quiche for breakfast, lunch, or even a light dinner.

Let me start by saying I have zero qualms when it comes to crust on quiche. One of my favorite recipes on the site is Asparagus Quiche made with whole wheat flour. It’s just that I don’t always want the mess that comes with making the crust and with so many dietary restrictions in the world, making crustless quiche is an easy way to make sure everyone is cared for and I keep my sanity. 

This spinach and mushroom crustless quiche recipe is both vegetarian and gluten-free, but it’s so easy to adapt to your personal preferences. I have used this recipe as a base and swapped in broccoli, cheddar, and diced ham, or for a summery version tomatoes, roasted red peppers, and feta are delicious. I’ve even been known to make the most of roasted vegetables by transforming the leftovers into quiche. Really when it comes to crustless quiche anything goes.

Table of Contents

1. Ingredients in this Crustless Quiche Recipe
2. How to Make Crustless Quiche
3. How to Adapt this Recipe 
4. Make it a Meal
5. More Egg-cellent Egg Recipes
6. Crustless Quiche with Spinach and Mushrooms Recipe

Ingredients in this Crustless Quiche Recipe

Just a dozen ingredients (including salt and pepper) and this crustless quiche is the oven. Quiche is endlessly flexible. Not a mushroom fan? Just leave them out? A simple spinach quiche is pretty good too. 

• Eggs are the key to creating a delightfully fluffy and creamy texture adding richness and binding all the ingredients together.
• Whole milk lightens the eggs and is lower in calories and saturated fat than the more commonly used heavy whipping cream. 
• Fontina cheese has a smooth and nutty profile I like with mushrooms, but you could also swap it for mozzarella or goat cheese, a couple of favorites of mine. 
• Olive oil not only adds a touch of healthy fat but also helps the crustless quiche release from the pie plate. Olive oil is the fat of choice in the Mediterranean diet so I use it in place of butter any chance I get.
• Baby spinach leaves are such an easy way to add a few extra vegetables to your diet.
• Sliced mushrooms are a natural source of Vitamin D and according to the National Library of Medicine, “… Mushrooms [could] be the only non-animal, unfortified food source of vitamin D that can provide a substantial amount of vitamin D2 in a single serving.” I eat mushrooms because they taste great, but it doesn’t hurt to know they are also a good source of Vitamin D.
• Yellow onion provides a subtle sweetness that balances out the other ingredients.
• Garlic, onions, and mushrooms are like a flavor-boosting dream team. 
• Thyme is one of my all-time favorite spices. In the summer when my garden is growing, I will use fresh thyme, in the winter dried. Either will work in this recipe.  
• Kosher salt plays a fundamental role in enhancing and balancing flavors while black pepper provides a subtle heat.
• Balsamic vinegar adds a slight tang infusing the crustless quiche with a unique depth of flavor and a delightful balance of acidity. When I was a teenager, my friend’s mom used to make us mushrooms on toast, and it was loaded with garlic and balsamic vinegar. I added it to this recipe to pay homage to her. If you don’t have balsamic vinegar you can leave it out. The recipe will still taste great.

How to Make Crustless Quiche

This crustless quiche recipe really couldn’t be any easier. I make it because I don’t always want to bother with making a pie crust, but it’s great for friends who are gluten-free or watch their carbs.  

• Preheat the oven and prepare the pan: Preheat the oven to 375°F. Brush a 9-inch pie plate with olive oil and set it on a baking sheet.
• Whisk the eggs and cube the cheese: In a large bowl, aggressively whisk together the eggs and milk. Cube the Fontina cheese and set aside. 
• Prepare the vegetables: Set a large skillet over medium-high heat. Add 1 tablespoon olive oil to the skillet. Once the oil begins to shimmer, add the mushrooms, onion, and minced garlic. Sprinkle with thyme, salt and pepper. Cook until the mushrooms shrink and the onions are translucent, about 10 to 15 minutes depending upon the size of your mushrooms. Drizzle the balsamic vinegar over the vegetables and stir, cooking for another minute or two. Add the spinach, and stir until wilted, this should take about 3 minutes. Taste and adjust the seasoning to your liking. 
• Combine: Add the cooked vegetables to the pie plate, sprinkle with the cubed cheese, and pour the egg mixture over the top. It should be full up to the rim. Carefully transfer the baking sheet to the oven.
• Bake: Set the timer for 35 minutes and bake until the center is set. Let cool at room temperature for about 10 minutes before serving. 

How to Adapt this Recipe 

We have quite a few egg recipes at The Mediterranean Dish because eggs are an affordable protein and are endlessly adaptable. Here are some of my favorite ways to keep my crustless quiche recipe fresh: 

• Summer Crustless Quiche: When my garden is exploding with fresh vegetables I like to swap the mushrooms and spinach with 1 cup of sweet corn kernels, a handful of cherry or grape tomatoes, and a little goat cheese. It’s one of my favorite combos. 
• Keep things simple: Spinach crustless quiche is great. Skip the balsamic vinegar and mushrooms in this recipe, add a 1/4 teaspoon of nutmeg and an extra cup of baby spinach. 
• Loaded Mushroom Crustless Quiche: Skip the spinach, double the mushrooms, but mix them up! Use a combination of oyster mushrooms, porcini mushrooms, and cremini mushrooms. We kind of have a thing for mushrooms around here. We like Marinated Mushrooms, Mushroom Pasta and we even put mushrooms in soup.
• Italian-inspired Quiche: Take a page out of our Breakfast Strata recipe and load this crustless quiche recipe with roasted red peppers, prosciutto, spinach, 1 teaspoon of Homemade Italian Seasoning, and a mixture of cheeses like parmesan and chèvre.  

Make it a Meal

On Sundays, I usually make a couple of salads that keep well in the fridge and about once or twice a month, I make this mushroom and spinach crustless quiche (or some quiche variation) to go with the salads. Then eat it for lunch or breakfast all week long.

It’s an easy way for me to make sure I get a decent, whole meal without a lot of effort. If left to my own devices I will snack. However, it’s also a great recipe for brunch or casual Saturday morning get-togethers.

Pair crustless quiche with a nice Fruit Salad loaded with fresh summery berries in the warmer months or for extra vegetables try it with Lemon Parmesan Lettuce Salad or this herby Greek Salad called, Maroulosalata. All the salads will last for days in the fridge, which makes mealtime a breeze.   

If salad isn’t your thing quiche goes well with soup too. Try it with this, Healthy Potato Soup or this rich and hearty Vegetable Stew.

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