Zucchini & Squash Casserole

This comforting zucchini and squash casserole is pure summer magic on a plate! Families absolutely love how the pesto adds that fresh herbal flavor while making the most of your garden bounty. Plus, it’s the perfect way to use up all that zucchini and yellow squash when your garden is overflowing.

Recipe Details

Timing & Servings: Active Time: 35 minutes, Total Time: 1 hour 15 minutes, Serves: 8 people.

Nutrition Profile: Low-Carb, Low-Sodium, Vegetarian.

Nutrition Facts (per serving): 255 Calories, 20g Fat, 12g Carbs, 8g Protein.

Ingredients You’ll Need

Unsalted butter: You’ll need 1 tablespoon divided in half for cooking the veggies. This adds such a nice rich flavor to both the zucchini and squash.

Zucchini: 1½ pounds of zucchini, which is about 4 medium ones, sliced ¼ inch thick. Try to keep your slices even so everything cooks at the same rate!

Yellow onion: 1½ cups thinly sliced onion, divided between the two veggie batches. The onions get so sweet and tender when cooked with the squash.

Yellow squash: 1½ pounds of small yellow squash, sliced ¼ inch thick. Small squash tend to be more tender and have fewer seeds.

Large eggs: 2 eggs help bind everything together and give the casserole that perfect creamy texture.

Canola mayonnaise: ½ cup adds richness and helps create that amazing creamy base for the casserole.

Pesto: ¼ cup of pesto brings all those wonderful herbal flavors – you can use store-bought or homemade!

Salt: Just ⅛ teaspoon since the pesto and cheeses already add plenty of flavor.

Mozzarella cheese: ½ cup shredded low-moisture mozzarella melts beautifully throughout the casserole.

Panko breadcrumbs: ½ cup creates that golden, crunchy topping we all love on casseroles.

Parmesan cheese: ¼ cup grated Parmesan adds that nutty, sharp flavor to the crispy top.

Cooking spray: Just a light coating helps the topping get perfectly golden brown.

How to Make Zucchini & Squash Casserole

Step 1: Place your oven rack in the middle position and preheat to 375°F. Melt ½ tablespoon butter in a large nonstick skillet over medium-high heat. Add the zucchini and ¾ cup of onion. Cook, stirring often, until the center of the zucchini is very tender and translucent, about 10 to 12 minutes. Transfer this mixture to a colander set over a bowl.

Step 2: Repeat the same process with the yellow squash. Use the remaining ½ tablespoon butter and ¾ cup onion. Add the cooked squash mixture to the colander with the zucchini. Let everything drain for 5 minutes.

Step 3: Using a rubber spatula, gently stir and press down on the zucchini-squash mixture. You want to extract as much liquid as possible without mashing up the squash. Discard all that liquid – this step is super important for preventing a watery casserole!

Step 4: Whisk the eggs, mayonnaise, pesto and salt together in a large bowl. Gently fold in the drained zucchini-squash mixture and the mozzarella cheese. Spoon everything into a broiler-safe 2-quart baking dish.

Step 5: Combine the panko and Parmesan in a small bowl. Sprinkle this mixture evenly over the casserole. Lightly coat the panko mixture with cooking spray. Bake until golden brown in spots, about 30 minutes.

Step 6: Set your oven to broil without removing the casserole. Broil until the topping is golden brown all over, about 2 to 3 minutes. Let the casserole stand for 5 minutes before serving – this helps it set up perfectly!

Easy and Quick Zucchini & Squash Casserole Version

Want to speed things up? You can skip the draining step if you’re short on time! Just cook the veggies until most of the liquid has evaporated, about 15 minutes instead of 10-12. The casserole might be slightly more moist, but it’ll still taste amazing. You can also use pre-shredded cheeses to save a few minutes of prep time.

Serving Ideas

This hearty casserole makes a complete meal on its own! Serve it alongside some crusty garlic bread and a simple green salad. It also pairs beautifully with grilled chicken or fish if you want to add some protein. The fresh pesto flavors make it perfect for summer dinner parties too!

Storage

Store leftover casserole covered in the refrigerator for up to 4 days. To reheat, cover with foil and bake at 350°F for about 15-20 minutes until heated through. You can also reheat individual portions in the microwave for 1-2 minutes, though the topping won’t be as crispy.

Substitutions

No pesto? Try using ranch dressing or herb cream cheese instead! You can swap the mozzarella for cheddar or Swiss cheese. Regular breadcrumbs work fine if you don’t have panko. And if you’re out of yellow squash, just use all zucchini – it’ll be just as delicious!

Pro Tips

• Don’t skip the draining step: This is the secret to avoiding a watery casserole that nobody wants!

• Slice evenly: Try to keep your veggie slices the same thickness so everything cooks evenly.

• Use a broiler-safe dish: Make sure your baking dish can handle the broiler for that perfect golden top.

• Let it rest: Those 5 minutes of standing time really help the casserole hold together when you serve it.

FAQs

Can I make this casserole ahead of time?

You bet! You can assemble the whole casserole up to a day ahead, cover it, and keep it in the fridge. Just add about 5-10 extra minutes to the baking time since it’ll be cold. The flavors actually get even better overnight!

What if my casserole seems too watery?

No worries! This usually happens if you skip the draining step or don’t press out enough liquid. Next time, really press down on those cooked veggies to get all that moisture out. If it’s already baked and watery, just let it sit for 10 minutes – it’ll firm up as it cools.

Can I freeze this casserole?

Sure! This casserole freezes well for up to 3 months. Let it cool completely, then wrap it tightly. Thaw overnight in the fridge and reheat covered at 350°F until heated through. The texture might be slightly different, but it’ll still taste great!

What’s the best way to slice the vegetables?

A sharp knife works perfectly, but if you have a mandoline slicer, that makes quick work of getting even slices! Just be super careful with your fingers. Aim for slices that are about the thickness of a quarter – not too thin or they’ll get mushy, not too thick or they won’t cook through properly.

I’d love to hear how this casserole turns out for you! Did you try any fun variations or substitutions? Drop a comment and let me know – I always enjoy hearing about your cooking adventures!