Wonderfully flavorful crustless onion quiche with cheese is an easy recipe that yields impressive results. It’s also keto and gluten-free.
The idea for this delicious quiche came from a reader. I used to have a recipe for mini onion quiches on this blog. When John Razzano emailed me to ask if he could make them in a 9-inch pie plate, I was intrigued. It sounded doable and easy!
John reported back that indeed, the recipe worked (he simply baked it for a little longer), and sent a gorgeous photo. So obviously, I just had to make it too! I did make a few small tweaks (amazingly, I can’t even make my own recipes without tweaking them).
The ingredients you’ll need
You’ll only need a few simple ingredients to make a crustless onion quiche (the exact measurements are listed in the recipe card below):
Olive oil: I love cooking with this delicious oil. But if you’d rather use an oil with a higher smoke point, you can use avocado oil instead. Another tasty option is to use butter.
Onions: You can use white or yellow onions. Slice them thinly. Make sure you use fresh onions in this recipe. Frozen will not work.
Kosher salt and black pepper: If using fine salt, you should reduce the amount you use, or the quiche could end up too salty.
Eggs: I use large eggs in almost all of my recipes, this one included.
Greek yogurt: You can also use sour cream. In fact, sour cream will probably taste better.
Ground nutmeg: Adds a nice layer of flavor to the quiche. Make sure it’s fresh – a stale spice can easily ruin a dish. Speaking from a sad experience…
Coconut flour: I love using this gluten-free flour substitute. It’s highly absorbent, so it’s best to measure it by weight and not by volume.
Shredded cheddar: You can experiment with other cheese. Gruyere is also great in this recipe.
How to make a crustless onion quiche
Scroll down to the recipe card for the details. But the basics are easy:
1. Your very first step is to cook some onions in olive oil (or in butter) until browned.
2. Now add the cooked onions to a seasoned mixture of eggs, Greek yogurt (or sour cream), and coconut flour.
3. Then pour the mixture into a greased standard-size pie plate and bake until set and golden brown. This should take about 40 minutes in a 350°F oven.
What to serve with this quiche
What about leftovers?
You can keep the leftovers in the fridge, in an airtight container, for up to 4 days. They keep well – they’re almost as good as the freshly made quiche.
Reheat the leftovers gently in the microwave on 50% power. They’re also good cold! Sometimes I grab a slice straight out of the fridge and have it as a quick snack.
More tasty quiche recipes
Enjoyed this crustless onion quiche? Well, I have several quiche recipes on this blog in case you’d like to try more recipes. A couple of favorites are crustless vegetable quiche and eggplant quiche. Both are very flavorful and VERY easy to make.
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Crustless Onion Quiche
- Olive oil cooking spray
- 1 tablespoon olive oil
- 2 medium onions, thinly sliced (12oz)
- 1 teaspoon Diamond Crystal kosher salt divided
- 6 large eggs, lightly beaten
- 1/2 cup plain Greek yogurt
- 1/4 teaspoon ground pepper
- 1/8 teaspoon ground nutmeg
- 1/4 cup coconut flour (1 oz)
- 1/2 cup shredded sharp cheddar
- Preheat oven to 350 degrees F. Spray a 9-inch pie plate with nonstick cooking spray.
- Heat the olive oil in a large, deep skillet over medium-high heat, about 2 minutes. Add the onions and 1/2 teaspoon kosher salt and cook, stirring often, 8 minutes, until lightly browned. Remove from heat and allow to slightly cool.
- Meanwhile, in a large bowl, whisk together the eggs, yogurt, 1/2 more teaspoon kosher salt, black pepper, nutmeg and coconut flour. Using a spatula, mix in the cheese and the caramelized onions.
- Transfer the mixture to the prepared pie plate. Bake 40-45 minutes, until puffed and set and a toothpick inserted in the center of the quiche comes out clean.
- Remove from oven. Cool 10 minutes in the baking dish on a cooling rack, then carefully run a knife around the edges to loosen. Invert onto a cutting board, then back to the cooling rack to finish cooling, about 10 more minutes.
- Carefully transfer the quiche back to the cutting board. Use a sharp knife to cut into 6 slices, and serve.