I love all forms of egg casserole. They are an easy, vegetarian way to boost your protein intake, and they usually make it easy to incorporate a few extra vegetables in your daily routine. This crustless quiche uses fresh mushrooms and tomatoes to create a flavorful breakfast (or dinner) dish that works well for meal prep. A few secret ingredients combine with the eggs to make a “magic” crust that forms while the quiche is in the oven.

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This crustless quiche was inspired by my mother-in-law’s recipe for “impossible quiche” . Her version utilizes Bisquick to create the crust at the bottom of the dish, but when I went to make this recipe on a busy weeknight, I realized we had forgotten to pick up the mix at the grocery store. Call me lazy or call me efficient, but I made the best of the situation and created a version that instead used the flour and baking powder I already had on hand.

A slice of crustless quiche sits on a white plate rimmed with gold. Tomatoes and mushrooms are visible within the quiche, and you can just barely discern a thicker crust that has formed in the lower portion of the slice.

I love using this crustless quiche as a meal prep recipe, or as a dinner idea when we have a lot going on. Obviously, it also works as a spectacular breakfast or brunch item, especially if you are hosting guests. If you’re looking for another dish to add to your breakfast or brunch menu, check out this overnight French toast casserole, or maybe my mom’s famous cinnamon rolls.

This quiche is also handy because it is endlessly versatile. The version listed below uses onions, tomatoes, and mushrooms, but you can add whatever vegetables you prefer. My husband loves when we add strips of cooked bacon or ham to the mix. The only caveat you should keep in mind if going “off-recipe”: only use about 1/4 to 1/2 cup of filling per egg. For this recipe, that would mean 1-2 cups of filling total. Baking is all about chemistry, and too much ratio adjustment can negatively impact your final product.

Ingredients

While you may still need to run to the grocery to pick up a few things, you might already keep all of the ingredients for a crustless quiche on hand.

Avocado oil
Diced onion
Diced tomatoes (I prefer fresh, but canned and drained also work fine)
Crimini or Baby Bella mushrooms
Spices – oregano, basil, and minced garlic
Eggs
Milk
Flour
Baking Powder
Cheese – we like to use both cheddar and parmesan.

How to make crustless quiche

Grease a 9” pie pan and set it aside. Preheat the oven to 375 degrees F.

Pour 1 tablespoon of avocado oil into a medium saucepan and turn the heat to medium. Once the pan is hot, add the diced onion and sauté until translucent. Add in diced tomatoes and cremini mushrooms, cooking until the mushrooms have released their liquid.

Stir in the minced garlic and cook the mixture for an additional 1 minute, until it is aromatic. Remove from the heat, drain off any extra juices, and spread this mixture evenly in your prepared pie pan. Cover the sautéed vegetables with an even layer of shredded cheddar cheese.

In a blender or large mixing bowl, beat together the 4 eggs before adding in the milk. Mix in the flour, baking powder, and spices, and then blend or beat vigorously to ensure the mixture is smooth. Pour your egg mixture into the pie pan. Sprinkle with parmesan.

Place the pie pan on a baking sheet and transfer to your preheated oven. Bake for 40-50 minutes at 375 degrees F, until a toothpick inserted in the center of the quiche comes out clean.

If you’re making this recipe for meal prep, or if you want to prepare a breakfast option to eat on the run, you can follow the same procedure to make crustless quiche muffins, or crustless mini-quiches. Simply use a well-greased muffin pan instead of a pie plate; the listed ingredients will make 18 mini-quiches. Start checking for doneness closer to 35 minutes of cook time, as they will require significantly less time in the oven. These mini quiches can be refrigerated for up to 10 days, or sealed well and frozen for several weeks.

I hope this crustless quiche met all of your expectations! Do let me know if you tried this recipe at home – either by leaving a message in the comments below, or by tagging your photos on social media @WhiskAverseBaking. You can also save this to your Pinterest boards by clicking “Pin Recipe” in the recipe card.