Zucchini Casserole

This creamy cheesy zucchini casserole includes tender discs of summer squash baked with cheese, onion, and garlic followed by a topping of crisp panko breadcrumbs. Pop it in the oven until bubbly and golden!

Why this recipe works

Put your abundance of garden squash to good use with this easy zucchini casserole loaded with creamy, cheesy goodness. Top with panko breadcrumbs for a little crunch and texture, or leave it off for a low-carb side dish bursting with savory flavors.

I like to call this casserole zucchini au gratin because it’s very similar to cheesy au gratin potatoes and is prepared in the same fashion.

Ingredients you will need

Get all measurements, ingredients, and instructions in the printable version at the end of this post.

Ingredient Info and Substitution Suggestions

ZUCCHINI – Due to zucchini’s naturally high water content, we are going to saute the slices before baking. This will help draw a little moisture out while adding a nice crust. You can easily substitute the zucchini with yellow squash or include a mixture of the two.

CHEESE – We chose a combination of both cheddar and Monterey jack cheese. You can use old cheddar, mild, or sharp. Havarti, Gouda, or Muenster cheese are great substitutes for Monterey jack.

MAYO – The mayonnaise is what makes this casserole creamy, I would not suggest leaving it out.

How to Make Zucchini Casserole

These step by step photos and instructions are here to help you visualize how to make this recipe. You can Jump to Recipe to get the printable version of this recipe, complete with measurements and instructions at the bottom.

1. Preheat your oven to 350F. Coat a 7×11 baking dish with non-stick cooking spray and set aside.
2. In a large skillet, heat oil over medium heat. Lightly sauté sliced zucchini, chopped onion, garlic, Italian seasoning, and salt for 5 minutes or until vegetables start to soften.
3. Remove skillet from heat and stir in the cheddar cheese and 2 ½ cups of Monterey Jack cheese. Mix in mayonnaise until fully combined.
4. Add cheesy zucchini mixture to the prepared baking dish and sprinkle on the remaining cup of Monterey Jack cheese.
5. Cover with foil and bake for 25-30 minutes (Tip: spray the foil with non-stick spray to prevent the cheese from sticking).
6. Just prior to removing the casserole from the oven, melt the butter and combine it with the Panko breadcrumbs in a small bowl. Evenly sprinkle the casserole with the panko mixture.
7. Move your oven rack to the second highest level and broil, uncovered, until golden. Keep a close eye on it, it won’t take long!
8. Garnish with fresh chopped parsley and serve.

Frequently Asked Questions & Expert Tips

Yes, you can freeze this casserole. To freeze the finished (baked and cooled) casserole, wrap it in plastic wrap followed by a layer of aluminum foil and freeze for up to 3 months. Thaw at room temperature and bake according to directions. You can freeze the unbaked casserole following the same method but it may be too watery once thawed.

Store any leftovers in an air-tight container kept in the refrigerator for 3-4 days. Reheat in a 350F oven for 10-15 minutes or until warmed through.

Serving Suggestions

Serve zucchini casserole with just about any main course from chicken, beef, pork, and fish or enjoy it as a cheesy vegetarian side dish. Optionally leave the panko breadcrumbs off as an even lower-carb alternative.

More Zucchini Recipes

• Grilled Zucchini
• Sauteed Zucchini
• Zucchini Pizza Bites
• How To Make Zucchini Noodles
• Grilled Corn and Zucchini Salad with Feta
• Zucchini Fritters

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