Name: Mushroom Quiche with Creamy Custard and Gruyère Recipe
Prep time: 20 min
Cook time: 40 min
Total time: 60 min
Ingredients: 1 (9-inch) refrigerated pie crust; 2 tablespoons unsalted butter; 1 medium yellow onion, thinly sliced; 2 cloves garlic, minced; 8 ounces cremini mushrooms, sliced 1/4 inch thick; 4 large eggs; 1 cup heavy cream; 1/2 teaspoon kosher salt; 1/4 teaspoon black pepper; 1/4 teaspoon ground nutmeg; 1 1/2 cups shredded Gruyère cheese

This mushroom quiche with creamy custard and Gruyère turns a simple dinner into something you look forward to all day. Savory sautéed mushrooms and sweet onions sit in a buttery crust under a silky egg filling.

It’s a reliable make-ahead meal that reheats beautifully for lunch the next day, and it comes together with mostly pantry staples.

What Makes This Mushroom Quiche So Good

I keep coming back to this quiche because the mushroom filling stays moist and deeply savory without ever getting watery. Sautéing them until they release their liquid and start to brown concentrates their earthy flavor.

The custard is just eggs, cream, and a pinch of nutmeg, which lets the mushrooms and salty Gruyère take center stage. Every bite has that contrast of flaky crust and tender interior.

Ingredients

1 (9-inch) refrigerated pie crust: from the dairy aisle, or use homemade if you prefer.
2 tablespoons unsalted butter
1 medium yellow onion, thinly sliced
2 cloves garlic, minced
8 ounces cremini mushrooms, sliced about 1/4 inch thick: white button mushrooms work too.
4 large eggs
1 cup heavy cream: half-and-half works but the quiche won’t be quite as creamy.
1/2 teaspoon kosher salt
1/4 teaspoon black pepper
1/4 teaspoon ground nutmeg: fresh grated is even better.
1 1/2 cups shredded Gruyère cheese: Swiss or sharp cheddar are good swaps.

Variations / Substitutions

Add fresh herbs: stir 1 tablespoon chopped thyme or chives into the custard for a fresh note.
Swap the cheese: Gruyère is classic, but sharp cheddar, fontina, or even smoked Gouda all work beautifully.
Make it meaty: stir in 4 strips of cooked, crumbled bacon or 1/2 cup diced ham.
Dairy-free: use a dairy-free pie crust, plant-based cream, and your favorite vegan cheese shreds; the custard will be a bit softer but still delicious.
Mix mushrooms: combine cremini with shiitake or oyster for a deeper woodsy flavor.

If you like this, you might also enjoy our spinach and feta tart.

How to Make Mushroom Quiche with Creamy Custard and Gruyère

Step 1: Sauté the Mushrooms and Onions

Preheat the oven to 375°F (190°C). In a large skillet, melt the 2 tablespoons of butter over medium heat. Add the sliced onion and cook, stirring occasionally, until soft and starting to turn golden, about 5 minutes. Stir in the 2 cloves minced garlic and the 8 ounces of sliced mushrooms, along with a small pinch of salt.

Sauté until the mushrooms release their liquid, the pan dries out, and the edges begin to brown, 8 to 10 minutes. This step concentrates the flavor and keeps the quiche from turning watery. Remove the pan from the heat and let the mixture cool for a few minutes while you prepare the custard.

Step 2: Whisk the Custard

In a medium bowl, whisk together the 4 large eggs, 1 cup heavy cream, 1/2 teaspoon salt, 1/4 teaspoon pepper, and 1/4 teaspoon nutmeg until smooth and fully combined. You’re not looking for bubbles, just a uniform pale yellow mixture.

Set the bowl aside near your work area. This whisking takes only a minute, and you’ll use it right after layering the filling.

Step 3: Assemble the Quiche

Unroll the refrigerated pie crust and gently press it into a 9-inch pie plate (or a deep-dish pie plate), making sure it fits snugly up the sides. No need to blind bake unless your crust tends to get soggy, though you can if you prefer (see Tips). Sprinkle half of the shredded Gruyère (about 3/4 cup) evenly over the bottom of the crust.

Spoon the mushroom and onion mixture over the cheese, spreading it in an even layer. Top with the remaining 3/4 cup of Gruyère. Slowly pour the custard over everything, letting it seep between the mushrooms. It will look like a lot of liquid, but the eggs will set it into a tender custard as it bakes.

Step 4: Bake the Quiche

Carefully transfer the quiche to the middle rack of the preheated oven. Bake until the edges are puffed and the center is just set—it should jiggle only slightly when you nudge the pan—about 35 to 40 minutes. If the crust starts browning too quickly, cover the edges with foil or a pie shield after 20 minutes.

The quiche will smell nutty and deeply savory. Let it cool on a wire rack for at least 10 minutes before slicing; it finishes setting during this rest and cuts much more cleanly.

Step 5: Slice and Serve

Run a thin knife around the edge of the crust to loosen it, then slice the quiche into wedges. A serrated knife works well to get through the crisp crust without tearing the custard.

Serve warm or at room temperature, with a simple green salad on the side. Any leftover slices keep well for days.

A Few Notes Before You Start

If you’ve had trouble with a soggy bottom crust, pre-bake the empty pie shell for 10 minutes at 375°F. Brush it lightly with beaten egg white before adding the filling; that seals the crust and keeps it crisp.
For the best texture, avoid over-whisking the custard. Too many air bubbles can make the quiche puff and then fall.
Slice the mushrooms by hand if you want varied textures, or use a food processor’s slicing disk for speed; either way, try to cut them uniformly so they cook evenly.
Because Gruyère is already quite salty, taste the sautéed mushroom mixture before seasoning the custard. You may want to start with a little less salt and adjust from there.

Storing Leftovers

Refrigerate: Cover leftover quiche tightly with plastic wrap or transfer slices to an airtight container. It will keep for up to 4 days in the fridge.
Reheating: To rewarm, place slices on a baking sheet in a 325°F oven for 10 to 15 minutes, or until heated through. The microwave works in a pinch but makes the crust softer.
Serve Cold: This quiche is also delicious straight from the fridge, making it an easy packed lunch.

What to Serve With Mushroom Quiche

A crisp green salad with a sharp vinaigrette cuts through the richness of the custard. For a heartier meal, roasted asparagus or steamed green beans with lemon add brightness. If you’re serving it for brunch, a bowl of fresh fruit or a simple tomato soup rounds out the plate.

Frequently Asked Questions

Why does my quiche turn out watery?

Usually, the mushrooms weren’t cooked long enough to release their liquid. Make sure you sauté them until the pan is dry and they’ve started to brown.

Can I freeze mushroom quiche?

Yes. Cool it completely, then wrap tightly in plastic wrap and foil. Freeze for up to 2 months. Thaw in the refrigerator overnight and reheat in the oven.

What’s the best mushroom variety for quiche?

Cremini (baby bella) mushrooms have a deep, earthy flavor that holds up well. White button mushrooms are milder but work fine; a mix with shiitake or oyster adds complexity.

Can I use milk instead of heavy cream?

You can, but the custard won’t be as rich and may have a slightly looser set. For the closest result, use whole milk; reduced-fat milks can make the quiche weepy.