Summer Squash Quiche with Fresh Thyme and Monterey Jack Cheese

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Squash is one of our favorite summer veggies, and we grow and eat a lot of it every year. While I honestly don’t get tired of having fried or grilled squash as a side dish with dinner three or four (or five or six) nights a week, it IS nice to change things up and do something different with it every once in a while.

This summer squash quiche takes a humble side dish veggie into main course territory. Like a traditional quiche, it’s extremely simple to put together using an egg and cream custard base (and a generous amount of cheese, of course).

Fresh thyme, butter, and the texture and summer flavor from the squash make this quiche something special. I make it regularly for a “meatless Monday” dinner while summer squash is in season, and it’s also perfect for a hearty but not overly rich breakfast/brunch dish.

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Ingredients for Summer Squash Quiche

Large (Deep Dish) Pie Crust

You can use either store-bought or homemade pie crust for this recipe. If you’re going with store-bought, I recommend the roll-out crusts rather than the type that come in a disposable pan (you’ll find them near the canned biscuits and puff pastry dough).

Can you make it crustless? Technically, yes, it’d probably work out alright to omit the crust altogether. However, this is a custard-style quiche that goes light on the eggs, not a frittata, so it might not hold together perfectly during serving without the crust.

Yellow Squash (or Zucchini)

For this recipe, it’s ideal to use summer squash that’s been picked on the small side (5 inches or less). Smaller squash will hold their texture better when cooked, while larger ones with more seeds tend to get a little mushy. You can also swap yellow squash for zucchini in this recipe, or use a combination of both.

Sweet Onion

Diced sweet onion (or yellow onions, if you like) gets sauteed in with the summer squash before going into the quiche filling. Shallots or leeks would also work wonderfully, if you want to get fancy.   

Heavy Whipping Cream and Eggs for Custard Base

While some quiche recipes call for half and half or even just milk, I think using heavy cream makes for the best set, flavor, and texture in the base. When I make traditional spinach, ham, and mozzarella quiche, I actually use a full cup of sour cream instead of heavy cream or half and half. For this squash quiche, though, heavy cream is perfect for balancing out the richness of the Monterey Jack cheese.

Note: If you have half and half or milk on hand but no heavy cream, you can use what you’ve got and add a dollop of sour cream to thicken up the mix. I’ve done this with good results.

Monterey Jack Cheese

Monterey Jack is my cheese of choice for this recipe, but you can use any freshly shredded cheese of your preference. Mozzarella or cheddar would also be great. Just keep in mind that cheddar cheese is quite a bit saltier than Monterey Jack or mozzarella, so you may want to reduce the salt a bit.

Note: It’s best not to use pre-shredded cheese for quiche. The anti-caking stuff they put in bagged cheese can really mess up the texture.

Butter

I use a decent-sized chunk of real butter to sauté my onions and squash for the quiche, since lightly browned butter, summer squash, and thyme pair really nicely together. If that’s just too much dairy for you, though, you can swap it for a mild-flavored sauté oil like avocado oil or olive oil.

Fresh Thyme

You can totally sub for dried thyme if you don’t happen to have any fresh, but that fresh thyme flavor is really what elevates this quiche!

Spices

I keep the spice blend pretty simple for this quiche: Salt, pepper, a little rubbed sage, and a generous dash of smoked paprika. That smoked paprika gives the quiche a boost of umami.

Steps for Making Summer Squash Quiche

Prepare the Crust

Roll out the crust and press it into a lightly greased deep dish pie pan. Feel free to trim the excess and make the edges look decorative by fluting them or pressing along them with a fork, if you like. I do it the “homestyle” way and fold any overhang under to make a thicker crust. I just can’t stand to waste any of that pie dough!

Do you need to pre-bake the crust? I never do, for quiche of any kind, regardless of whether I’m using store-bought or homemade crust. I find that the base of the crust will absorb some liquid from the raw filling whether prebaked or not; it’ll set to about the same texture either way after cooking.

Some folks swear by prebaking the crust for quiche, so it’s really a matter or preference. Just keep in mind that if you decide to prebake the crust, you may need to cover the edges with foil or a pie shield to keep them from over-browning about halfway through cooking.

Chop the Veggies

Slice the summer squash into rounds about one quarter inch thick or a little thicker. You want them thick enough they’ll hold up and keep their texture during cooking. If I have squash that are wider around on one end, such as crookneck varieties, I usually cut the larger parts into half-rounds so they’re easier to fit in the pie dish.

Next, dice your onions; for this recipe, I like to chop them pretty small so the flavor is there without any large bites of onion.

Sauté Squash and Onions

Melt the butter in a saucepan or skillet, add the diced onions, and cook them for two or three minutes on medium-low heat. Then add the squash, fresh thyme, smoked paprika, sage, and a dash each of salt and pepper. Cook, stirring every now and then, until the squash has started to brown and soften slightly. Since the squash will continue cooking in the quiche, you don’t want to cook it until it’s completely translucent here; crisp-tender is the goal.  

Make the Custard Base

While the squash and onions cook, lightly beat the eggs in a mixing bowl. Add the cream and ½ tsp. salt and whisk until the mixture is completely smooth.

Assemble the Quiche

First, transfer the sautéed squash and onions to the bottom of the pie crust. Arrange the shredded cheese in a layer on top of the veggies, then pour the egg and cream mixture evenly over everything. Don’t worry if your pie doesn’t look full enough at this point; the filling will puff quite a bit during cooking, which is why I recommend the deep dish.

Bake the Quiche

Bake at 350 F in a preheated oven for 45 – 50 minutes; you’ll know the quiche is done when the middle has set and doesn’t jiggle when you gently shake the dish. I tend to check mine at 35 minutes to see where I’m at, since you really don’t want to overcook a quiche. After baking, garnish the quiche with some extra fresh thyme leaves to make it pretty!

Note: Let the quiche cool for at least 20 minutes before cutting and serving. It will absolutely fall apart if you try to slice it right out of the oven.

Serving Ideas for Summer Squash Quiche

Since this quiche has your carbs, veggies, and some protein from the eggs, it makes for a well-rounded meatless dinner when paired with a side salad or maybe some sautéed greens and stewed potatoes. Or, serve it as an upscale weekend breakfast with some fresh fruit (and maybe a few slices of bacon).