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Served hot and bubbly, this cheesy casserole is the perfect way to use up an abundance of Summer squash.
Squash and Zucchini Casserole is a delicious Southern side dish made with yellow squash, zucchini, and fresh corn with a crunchy breadcrumb and Parmesan cheese topping.
With no cream soups, eggs, or mayonnaise, this easy casserole recipe is also healthier than some. Herb seasoned stuffing mix in the breadcrumb topping bakes up to make a perfect golden-brown Summer squash gratin.
Squash and zucchini casserole
We have a dilemma at our house. I enjoy cooking with Summer squash — small yellow squash and zucchini — but my husband has never really learned to enjoy eating it. I like it grilled, sautéed, and even eat it chopped up and raw on tossed salads.
He thought yellow squash and zucchini were disgusting… until now.
Lately, squash has been appearing in our weekly produce box giving me a good excuse to come up with a new recipe to use it up.
My in-laws were coming over for an outdoor cookout, so that was the perfect opportunity — there would be someone here to help me eat it!
Funny thing is, my hubby tried a bite. Then he tried another. And another. He actually said, “This is really good”!
Who knew?! Simply adding a little cheese and a crunchy topping could transform one of my favorite Summer vegetables into a dish that even my husband enjoyed. I’ve already made it twice, and trust me, I’ll be making it often from now on.
Key ingredients and substitutions
- Squash — yellow squash and zucchini squash
- Fresh corn
- Cheddar cheese — plus Parmesan cheese for the topping
- Sour cream
- Dry herb seasoned stuffing mix (like Pepperidge Farms) — I like the flavor of the herb seasoned stuffing mix for the breadcrumb topping, but you can also substitute panko breadcrumbs instead.
How to make Squash and Zucchini Casserole
STEP 1 | Prep the vegetables
- Choose small to medium-size yellow squash and zucchini for this dish. I like to use smaller ones because the larger ones can be bitter and the skins are tougher.
- With smaller squash, there’s no need to peel them or remove the seeds.
- Cut each squash/zucchini in half horizontally, then cut each half into two or three long strips. Dice the strips into one-half inch pieces. You should get about 6 cups of diced squash.
- Cut off the kernels from one ear of fresh corn and dice a small onion.
STEP 2 | Combine the ingredients
- Sauté onion and garlic in butter, then add the squash (yellow and zucchini) and corn and cook another 5 minutes.
- Remove it from the heat and stir in light sour cream and cheddar cheese, then dump it all in a casserole dish.
STEP 3 | Make the topping and bake
- Make the crunchy topping by combining herb seasoned stuffing mix (like Pepperidge Farms), parmesan cheese, and melted butter.
- Sprinkle the breadcrumb mixture on top of the casserole and bake until hot and bubbly. DELISH!
- If you do use the panko, you’ll want to toast them first before combining with the parmesan cheese and butter to make sure they are good and crunchy in the final dish.
Frequently asked questions
Both yellow squash and zucchini are packed with vitamins and beneficial nutrients. Yellow squash is a power veggie boasting vitamins A, B6, and C, folate, magnesium, fiber, riboflavin, phosphorus, and potassium — whew!
Zucchini is full of vitamins C and A, potassium, folate, and fiber — all good for a healthy heart, reducing high blood pressure, and lowering cholesterol.
Absolutely! When squash is bountiful, freezing it and saving it to use later is super easy to do. There’s no need to blanch it, just cut the squash into the size you’ll need for future recipes (diced, sliced, or shredded) and then seal it up raw in freezer bags. It will retain its flavor frozen for 4 to 6 months.
Other ways to cook Summer squash
With ALL that goodness and nutritional benefits, it’s a good idea to find more ways to include Summer squash in your family’s diet. Here are a few tasty ideas for how:
- IN LASAGNA. Healthy and super delicious, this Easy Skillet Vegetable Lasagna can be prepared AND cooked in less time than it takes to do the prep work (cooking the noodles and making the fillings) for a traditional baked lasagna.
- ON THE GRILL. Toss sliced zucchini, squash, onions, or peppers in olive oil and sprinkle with this easy Magic Rub recipe. Cook over direct heat for three or four minutes per side, or until the veggies are slightly charred and tender. EASY!
- BREADED AND BAKED. You’re gonna love how easy it is to make this healthy Baked Parmesan Squash.
- SPIRALIZED! “Zoodle” Ratatouille is a composition of seasonal vegetables — zucchini, onions, sweet bell peppers, and tomatoes — spiralized and cooked with olive oil and garlic. OR how about this super simple recipe for Spiralized Pesto Noodles that can be done in a short amount of time.
- IN A QUICHE. This veggie lover’s California Quiche is chock full of zucchini, peppers, onion, and artichoke hearts. Big bonus: one serving is under 250 calories!
- IN A SALAD. Grilled Summer Vegetable Pasta Salad is a mixture of delicious pasta mixed with the cream of the summer crops veggies, like squash!
- IN QUICK BREAD. Hide veggies in this healthier, most delicious zucchini snickerdoodle quick bread and no one will ever be the wiser!
- IN CHOCOLATE CAKE! Super rich and fudgy; studded with chocolate chips, frosted with creamy, chocolate buttercream — nobody will even know there’s zucchini hidden inside this Chocolate Zucchini Cake!
Summer Squash, Zucchini, and Corn Casserole
- 4 tablespoons unsalted butter divided
- 2/3 cup diced onion
- 1 clove garlic minced
- 3 cups diced zucchini squash 2 medium
- 3 cups diced yellow squash 2 medium
- 1 ear fresh corn cut off the cob
- 1 cup light sour cream
- 1 cup cheddar cheese shredded
- 1 teaspoon kosher salt
- 3/4 teaspoon black pepper
- 2 cups dry herb seasoned stuffing mix like Pepperidge Farms
- 1/4 cup grated parmesan cheese
- Preheat the oven to 350 degrees. Lightly coat a 9 x 13 inch baking dish with cooking spray.
- In a large skillet over medium heat, melt 2 tablespoons butter. Add the onion and cook for 5 minutes, until translucent. Add the garlic and cook until fragrant, about 30 seconds.
- Add the diced zucchini, squash, and corn to the skillet and cook for 5 minutes, stirring frequently.
- Remove the skillet from the heat and stir in the sour cream, cheddar cheese, salt, and pepper. Pour the mixture into the prepared baking dish.
- In a medium bowl, stir together the herbed stuffing mix, parmesan cheese, and 2 tablespoons melted butter. Sprinkle evenly over the casserole.
- Bake for 40 to 45 minutes, until the casserole is hot and bubbly. Let stand 10 minutes before serving.
About Sheila Thigpen
Recipe Developer, Food Photographer, Food Writer
Sheila Thigpen is the publisher of Life, Love, and Good Food — a Southern food blog — and the author of Easy Chicken Cookbook and The 5-Ingredient Fresh and Easy Cookbook. After 20+ years in the publishing industry, she retired in 2018 to focus on her own creative endeavors full time. She and her husband live near the beautiful Smoky Mountains and have a precious little granddaughter who has stolen their hearts. As an influencer, Sheila has collaborated with brands like Creamette, Kroger, HERSHEY’S, Hamilton Beach, Garafalo Pasta, OXO, Smithfield, Valley Fig Growers, and more.