Zucchini and Summer Squash Casserole is baked with fresh basil, roma tomatoes and sweet corn. An excellent side dish or tasty vegetarian main course.
Since there seems to always be a bounty of these squash, zucchini recipes abound and I have a few not-the-norm coming up for you in the next couple of weeks, including a Zucchini, Carrot, Banana Walnut Bread that is seriously the best quick bread I’ve ever made. And you really should try my Carrot and Zucchini Pancakes with Basil Chive Cream!
But back to the zucchini and summer squash casserole here. This recipe is a variation of a summer squash casserole that people who live in the southen U.S. frequently eat during barbecue and summer potluck season.
I found the key to success in this version is sauteing the squash before it’s baked with the other ingredients. Cooking the vegetables in a small amount of butter to soften them will add a nice caramelized flavor. Then before the squash is put into the baking dish, I gently pressed the squash to remove excess moisture (and most of the butter I cooked it in). The squash is placed in a colander after browning and then gently pressed with a rubber spoon and a LOT of juice comes out during this process. As you see in the photo above, my casserole still had a bit of liquid left in the dish, but it’s just enough to be tender but not soggy.
Zucchini and Summer Squash Casserole is almost like a veggie-loaded quiche because a few eggs whisked with milk act as the binder. Other flavorful ingredients include onions, garlic, cheddar and fresh corn kernels. But my favorite add-in is the chopped fresh basil! It brings everything together so perfectly that I recommend you only use fresh basil, not dried. And don’t even think of omitting it if you don’t have any. Wait until you do before making this recipe.
I added crushed crackers in the baking dish before adding the vegetables. The crackers on the bottom actually morph into a thin pie crust and even though it soaks up some of the juices from the vegetables and the egg mixture, it’s perfectly tasty and golden. The casserole is also topped with thinly sliced Roma tomatoes which add even more freshness and tasty color, and then finish with more cracker crumbs for the perfect crunchy buttery finish. After the Zucchini and Summer Squash Casserole comes out of the oven, it should cool for at least five minutes before cutting and serving to allow it to set. I was able to cut a pie shaped piece for the pictures but it’s easier to just spoon it out and not worry about it holding any sort of shape.
My 13-year old asked for a “taste” and he ate an entire helping; one of my go-to-taster girlfriends shared her sample with some neighbors and they all gave it the thumbs up and even wondered about making it with some Italian or Polish sausage cooked inside (I’ll have to try that and report back). I will frequently serve this as the main dish with a green salad on the side. You could pretty much find a way to fit Zucchini and Summer Squash Casserole into any menu but I promise it won’t be just another standard recipe made to get rid of all the zucchini in the house!
Zucchini and Summer Squash Casserole
- 3 Tablespoons butter, plus softened butter for the baking dish
- 1 large yellow onion, chopped
- 4 cloves garlic, minced
- 1 pound zucchini, cut into ½-inch rounds
- 1 pound yellow squash, cut into ½-inch rounds
- 1 cup fresh or frozen corn kernels
- 2 cups shredded sharp cheddar cheese
- 2 cups flaky crackers, such as Ritz, coarsely crushed
- 3 large eggs
- 1 ½ cups whole milk
- 3 Tablespoons fresh basil, chopped
- 1 teaspoon kosher salt- if using table salt, add less
- Freshly ground pepper, to taste
- ½ teaspoon hot pepper sauce such as Tabasco
- 2 Roma tomatoes, sliced thin
- Position a rack in the center of the oven and preheat to 350F degrees. Lightly butter a 13x9-inch or large round (11-inch) baking dish.
- Melt 1 Tablespoon butter in a large skillet over medium-high heat. Add 1 chopped onion and 4 minced garlic. Cook, stirring occasionally, until tender and just starting to brown, about 10 minutes. Transfer the mixture to a medium bowl.
- Melt another Tablespoon butter in the skillet, again over medium-high heat. Add 1 pound zucchini in a single layer and cook, stirring occasionally, until browned and tender, about 5 minutes per side. Transfer the zucchini to a colander and let it drain over a plate or in your sink. Melt 1 more Tablespoon of butter and add 1 pound yellow squash in a single layer and cook in the same manner as the zucchini. Add the yellow squash to the zucchini in the colander. Using a rubber spatula, press gently on the squash mixture to remove excess moisture. Stir the squash into the onion mixture and add 1 cup cheddar.
- Add 1 cup corn to this mixture.
- Since the skillet is still warm, I like to toss the corn into it and quickly brown it on medium-high before adding, this adds nice flavor to the corn but is not critical.
- Sprinkle 1 cup crackers in the bottom of the baking dish. Top them with the squash mixture.
- Whisk 3 eggs in a medium bowl. Add 1 ½ cups milk, 3 Tablespoons basil, 1 teaspoon salt, black pepper, ½ teaspoon hot sauce and whisk until combined.
- Pour the egg mixture evenly over the squash. Sprinkle the remaining 1 cup of cheddar over top, arrange 2 thinly sliced tomatoes over the cheese and then sprinkle the remaining 1 cup crackers over the tomatoes.
- Bake until the casserole feels set when pressed gently in the center, about 30-35 minutes. Let stand for 5 minutes and serve.
- You can substitute your favorite healthy oil for the butter, but the butter adds better flavor when browning plus remember you're pressing out a lot of it in the colander (do NOT use a butter substitute); I highly recommend using fresh basil and not omitting or substituting with dried, it makes a difference.
Recipe adapted from The Big Book of Sides.
harper williams says
This dish is SO DELICIOUS! I followed the recipe as is and everyone loved it. Not a crumb left over and I doubled the batch! Thank you for sharing Sally!
My family wanted more, especially me! Delicious!
lily s says
Made this for the first time this weekend! Wasn’t disappointed, turned out wonderful. Served it as a side dish with grilled chicken. Definitely make it again!
This recipe sounds wonderful! I like to make 2 casseroles at a time and freeze one, so I was wondering if this can be frozen for later? Thanks Sally, I just love your blog and recipes 🙂
brandy b says
This is exactly the kind of casserole I crave and I love that this doesn’t use canned soup!!
Oh my gosh. This is hands down the best way I could have used my zuccs and squash I had. I made a double batch and I’m sure I won’t tire of this. I have been raving about it by myself outloud in my apartment for the last 15 minutes and texting so many people this page so they can have the same mind blowing experience I did. The prep was long (especially since I’m a slow chopper) but oh so worth it. Oh my gosh.
Sally Humeniuk says
Thanks Valerina! I love that you were exclaiming out loud to yourself about it. I frequently do that about certain recipes, too. 🙂 And thanks for sharing the recipe with others!
This was delicious!! The flavors came together very well. Plus, its always nice to have new recipes for all of the zucchini days!!!
Thanks Kim, and I have a few more zucchini recipes coming up soon so stay tuned. 🙂
Kevin | Keviniscooking says
Looks scrumptious and I agree with the saute first. Once I had a soupy version, no bueno. The cheese and cracker topping are killer!