Caramelized Onion, Mushroom & Swiss Quiche

Caramelized Onion Mushroom Swiss Quiche-1254.jpg

In a decidedly un-me move, I made scratch pie crust the other night (the real gluten-y kind, true story). And then I used that crust to make this fantastic, fluffy, easy quiche with mushrooms, thyme, Swiss cheese and specifically these caramelized onions.

This quiche was v. good. Like, blog-about-it-on-the-first-try kind of good. I would even go as far as saying you will never need another quiche recipe, because you can use the same basic principles for almost any flavor combo as long as the volume and moisture levels of the fillings remain about the same.

Caramelized Onion, Mushroom & Swiss Quiche Recipe via Worthy Pause

I'm not going to pretend to be a pie crust expert because the crust in these pictures is literally the first normal pie crust I've ever made from scratch. I did do an almond flour pie crust for this ol' Paleo Pumpkin Pie, but that is a rather different animal than this.

To make sure it turned out nice and flaky, I turned to the trusty New York Times and their All-Butter Pie Crust. It's simple (only four ingredients and one is water). It works.

In addition to the real pie crust, this quiche is just full of dairy. That's the thing you just can't get around with a quiche — the dairy to egg ratio has to be pretty intense for the ultimate fluffiness. A typical quiche ratio is 1/2 cup cream to 1 large egg. For most normal-sized quiches, that's 2 cups of cream and 4 eggs. This recipe inches toward the egg side with 5 eggs and 1.5 cups of cream, but it is still fluffy as can be!

Before we get to the recipe, if you're mad at me for making a quiche you can't eat and are looking for something with a lot less gluten and dairy (my usual M.O. on Worthy Pause), these Paleo Bacon & Broccoli Egg Muffins are great (and portable). You could totally make them with caramelized onions, mushrooms and thyme and they would be excellent.

If you want the real deal, continue.

Caramelized Onion, Mushroom & Swiss Quiche Recipe via Worthy Pause

Caramelized Onion, Mushroom & Swiss Quiche

vegetarian (gluten-free with crust substitution) | serves 8


  • 1 pie crust (I used this all-butter recipe from the New York Times, but choose your own adventure here)

  • 1 large onion, thinly sliced

  • 2 T butter

  • 1 pint mushrooms, sliced into bite-sized pieces

  • 1/2 tsp thyme leaves (+ a few more sprigs worth)

  • black pepper, to taste

  • 5 eggs

  • 1.5 cups half-and-half or cream

  • 1 cup swiss cheese

  • pinches of salt, to taste

  • optional: a dash of cayenne pepper, to taste



  1. Preheat the oven to 350 F.

  2. Caramelize the onions. I have a 20-minute foolproof method for how to caramelize onions (suggested reading!), and you'll also need 1 T butter and a pinch of salt while you handle this step. Let them cool a little bit before you assemble the quiche.

  3. While the onions are cooking, take the rest of the butter and sauté the mushrooms with thyme in another pan until all the liquid cooks off. Season with salt and black pepper and let cool.

  4. Place your pie crust in a 9-inch pie plate and flute the edges. If desired, brush the edges of the crust with a bit of half-and-half or an egg wash.

  5. Whisk together the eggs and half-and-half in a large bowl. Add a pinch of salt and a little bit of cayenne pepper for a slight kick, if desired. Stir in the cheese.

  6. At this point, you can just mix everything together and throw it into your pie crust. However, I like to make sure there is an even distribution in my quiches, so here's what I suggest: Place about a third of the onions and mushrooms strategically on the pie crust and gently spoon a layer of the egg/cheese mixture on top. Then some more onions/mushrooms, then more egg/cheese. And then to make it look extra nice, save some stuff to float on the very top of the quiche and add a few more thyme leaves.

  7. Bake the quiche for about 50-60 minutes, or until a knife comes out clean from the center. Check the quiche around 35-40 minutes and if the crust is starting to brown too quickly, cover (just the crust or parts of it) with aluminum foil to protect it.

  8. Let rest for 5 minutes before cutting. Serve warm!



  • I made this quiche on a Thursday night at 11 pm and then ate it for 8 meals straight, so I know a thing or two about reheating it well. To reheat the whole quiche, bake for 30-40 minutes at 325 F. To reheat a piece of quiche, bake for 20-25 minutes at 325 F. (You could use a microwave, but the crust will get soggy and that's just the worst.)

  • You can make the onions, mushrooms and pie dough the night before and then assembly is very easy in the morning.

  • You could make a gluten-free version with a gluten-free pie crust or without the crust entirely. It'll bake a lot faster sans crust, so keep an eye on it after about 25 minutes.

Caramelized Onion, Mushroom & Swiss Quiche Recipe via Worthy Pause