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!
- 3 tablespoons butter plus softened butter for the baking dish
- 1 large yellow onion chopped
- 4 garlic cloves minced
- 1 pound zucchini cut into 1/2-inch rounds
- 1 pound yellow squash cut into 1/2-inch rounds
- 1 cup fresh or frozen corn kernels
- 2 cups shredded sharp cheddar cheese
- 2 cups coarsely crushed buttery flaky crackers, such as Ritz
- 3 large eggs
- 1 1/2 cups whole milk
- 3 tablespoons chopped fresh basil
- 1 teaspoon kosher salt if using table salt, add less
- 1/2 teaspoon hot pepper sauce such as Tabasco
- Freshly ground pepper to taste
- 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 of the butter in a large skillet over medium-high heat. Add the onion and garlic. Cook, stirring occasionally, until tender and just starting to brown, about 10 minutes. Transfer the mixture to a medium bowl.
- Melt another tablespoon of the butter in the skillet, again over medium-high heat. Add the 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 the butter and add the 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 of the cheddar.
- Add the corn to this mixture. Cook's note: 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 of the crackers in the bottom of the baking dish. Top them with the squash mixture.
- Whisk the eggs in a medium bowl. Add the milk, basil, salt, black pepper, hot sauce and whisk until combined.
- Pour the egg mixture evenly over the squash. Sprinkle the remaining 1 cup of cheddar over top, arrange the 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.
- Other notes: 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.
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. 🙂
Looks scrumptious and I agree with the saute first. Once I had a soupy version, no bueno. The cheese and cracker topping are killer!