Summer squash casserole is a fantastic option as a zucchini and squash medley. Definitely not the same old squash casserole you are used to, this casserole side dish is a great way to use up abundant summer gardens.
There is no doubt that vegetable casserole dishes like this yellow squash casserole are visually stunning. As such, they make perfect potluck side dish recipes because they taste as good as they look. When summer squash hits the store, you WILL BE READY.
Now to be completely frank, this dish isn’t the quickest. Prep on casseroles where vegetables have to be cut and ingredients have to be layered typically take a bit more work. But Southern dishes like this are work with a reason and this layered squash casserole is the PERFECT way to celebrate a blooming garden.
And can we talk about the panko crumbs? As a self proclaimed panko crumb fantastic, the simple yet golden brown panko crust gives this recipe an expensive look with an easy flair.
Summer Casserole Grocery List
This fabulous recipe will require a handful of ingredients that are not always available in personal pantries. Make sure you have the following or can pick up the following before proceeding to the instructions.
- White Onion – Sliced
- Salt & Pepper
- Minced Garlic
- Dried Thyme – you can most certainly use fresh Thyme but its easier in this dish to include the dried
- Fresh Basil – that being said, fresh basil is way better than dried so use the fresh here
- Dry White Wine – cooking wine is fine
- Kalamata Olives – chopped up into small pieces
- 2 pounds Fresh Zucchini – sliced 1/4th inch rounds
- 2 pounds Fresh Yellow Squash – sliced 1/4th inch rounds
- Panko Bread Crumbs
- Grated Parmesan
Yellow Squash Casserole Prep
Before you get started, preheat oven to 425 and grease a 9×13 baking pan.
Prep Casserole Ingredients
Add 2 tablespoons butter, onions, 1/2 teaspoon salt and 1/4 teaspoon pepper and heat over medium heat, stirring frequently until onions are soft and browned, about 10-12 minutes.
Stir in garlic and thyme and cook for 1 minute.
Stir in wine and cook until evaporated, about 2-3 minutes. Remove from heat and stir in olives. Set aside.
In a small bowl, combine panko bread crumbs, 1 teaspoon ground pepper and mix well.
Add zucchini and squash into a large microwave safe bowl and season with salt and pepper.
The easiest way to do this is to add a layer of zucchini, sprinkle with salt and repeat until the bowl is full. Cover and microwave for 8 minutes, stirring vegetables halfway through.
Carefully drain the dish in a colander (to remove excess moisture) and let cool.
Place a triple layer of paper towels onto a plate and add squash rounds. Put another layer of paper towel on top and gently press the liquid from the squash.
Sprinkle 6 tablespoons of bread crumb mixture onto the bottom of the baking pan.
Melt 4 tablespoons butter and mix with remaining panko mixture.
Arrange half of the zucchini and squash in the baking dish on top of the bread crumbs.
Sprinkle with 1/4 cup panko mixture and top with onion and olive mixture.
Arrange remaining zucchini and squash on top and cover with foil.
Bake casserole for 10 minutes.
Remove foil and discard.
Sprinkle with remaining bread crumbs and return to oven for 10-15 minutes or until golden brown and bubbling around edges.
Let stand for 15 minutes before serving.
Casserole Recipe Questions
Can Squash Casserole be made in advance?
Most casseroles hold up relatively well when assembled in advance. The key to any dish that is prepped and stored in the fridge is the change in temperature of initial ingredients. Once added to the fridge, food gets extra cold and needs to come up close to room temp prior to oven baking.
If you are going to make this one in advance to store, bring up to room temp about 30 minutes prior to baking. Additionally, do not add any topping or it will contain too much moisture. Add the final crumb layer just before baking.
What are the best variations or ingredients to add into the casserole to mix it up?
Not everyone is a fan of olives, so that can easily be left out. Additionally tomatoes go really well with squash and zucchini and can be added between slices. This is done in my zucchini tomato casserole recipe here.
Are there any other toppings that can be used?
Personally I would always opt for panko crumbs as they hold that delicious crunch so well. But you could always use Ritz Cracker topping like we did in Broccoli Cheese Casserole.
More Summer Vegetable Suggestions
Looking for more spring and summertime casserole recipe suggestions?
- Oven Baked Spaghetti Squash – once you learn how to oven bake spaghetti squash, it can be added in a ton of casseroles, eaten right out of the yellow squash boat as a stand alone dish or used as a low carb noodle solution!
- Zucchini Bread – if you haven’t tried zucchini bread yet, trust me. Its the summer equivalent of fall favorite pumpkin bread. Moist, delicious and worth the make!
- Oven Roasted Butternut Squash – Again, this recipe is a basic skill of learning how to make butternut squash, which can in turn be scooped and used for a variety of recipes – even baby food!
- Zucchini Tomato Casserole – if you missed this mention above, this squash casserole version is just SO GOOD and rated highly amongst readers here on Salty Side Dish!
- 6 tablespoons butter, divided
- 1 onion, sliced
- 1/2 teaspoon salt
- 1 teaspoon ground pepper
- 1 tablespoon minced garlic
- 1 teaspoon dry thyme
- 1/2 cup dry white wine
- 1/2 cup (4 oz.) pitted Kalamata olives, chopped
- 1/4 cup fresh basil
- 1-1/2 lbs. fresh zucchini, cut into 1/4" rounds
- 1-1/2 lbs. fresh yellow squash, cut into 1/4" rounds
- 1 cup panko bread crumbs
- 1 cup grated Parmesan cheese
Prep Onions & Olives
- Preheat oven to 425 and grease a 9x13 baking pan.
- Add 2 tablespoons butter, onions, 1/2 teaspoon salt and 1/4 teaspoon pepper and heat over medium heat, stirring frequently until onions are soft and browned, about 10-12 minutes.
- Stir in garlic and thyme and cook for 1 minute.
- Stir in wine and cook until evaporated, about 2-3 minutes. Remove from heat and stir in olives.
- Set mixture aside aside.
Steam Vegetables in Microwave
- Add zucchini and squash into a large microwave safe bowl and season with salt and pepper. I added a layer of zucchini and sprinkled with salt and repeated until the bowl was full.
- Cover bowl and microwave rounds for 8 minutes, stirring halfway through to ensure even cooking.
Remove Excess Moisture from Squash and Zucchini
- Drain vegetables of extra water in a colander.
- Once excess moisture is drained, place a layer of paper towels onto a plate and add squash and zucchini to the top.
- Add another layer of paper towel on top and gently press any excess liquid from the squash.
Assemble Casserole in Layers
- In a small bowl, combine 1 cup panko bread crumbs, 1 teaspoon ground pepper and mix well.
- Sprinkle 6 tablespoons of bread crumb mixture onto the bottom of the baking pan.
- Now melt 4 tablespoons butter and mix with remaining panko mixture.
- Arrange half of the zucchini and squash in the baking dish on top of the bread crumbs.
- Sprinkle the top with 1/4 cup panko & butter mixture and top that layer with onion and olive mixture.
- Arrange remaining zucchini and squash on top (as final layer) and cover with foil.
- Bake casserole in oven for 10 minutes.
- Remove foil and discard.
- Sprinkle the top of the dish with remaining bread crumbs and return to oven for 10-15 minutes or until crumbs are golden brown.
- Add a bit of fresh basil on top.
- Let stand for 15 minutes before serving to prevent it falling apart.
- This recipe is fairly "peppery" and so if you like less spice, cut pepper in half.
Amount Per Serving: Calories: 242Total Fat: 14gSaturated Fat: 8gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 34mgSodium: 532mgCarbohydrates: 22gFiber: 4gSugar: 6gProtein: 8g
Nutritional information is automatically calculated with ingredients and serving size and may not be accurate. Please always double check with your own nutritional apps as well.