Old Fashioned Zucchini Casserole

This old fashioned recipe for Zucchini Casserole is the perfect mix of fresh zucchini, dried herbs, and cheese with a biscuit coating.

slice of old fashioned zucchini casserole on a gray plate.

Old Fashioned Zucchini Casserole is the perfect way to give the humble zucchini LOTS of flavor!

It starts with plenty of zucchini, which gets paired with onions, dried oregano, and melty cheddar in this hearty veggie side dish. It also employs a shortcut ingredient: Bisquick! The biscuit mix helps hold everything together while lending a biscuit-like coating around the zucchini.

This casserole is truly a delightful side dish for the summer months. If you have more zucchini to use up, don’t miss this Chocolate Chip Zucchini Cake or Grandma’s Zucchini Muffins!

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old fashioned zucchini casserole in a gray square casserole dish, topped with cheese.

Top tips

  • Take care to cook this casserole all the way through. It has eggs in it, which can make it runny if undercooked.
  • You’ll need 6–7 cups of chopped zucchini. That’s roughly 4 small zucchini, or 2–3 medium. Thankfully, this recipe is forgiving if you use slightly more/less, so don’t sweat it if it’s a little over or under!
  • This casserole is best served the day it is made. If you have leftovers, you can reheat them in the oven.

Ingredients

zucchini, Bisquick, and other ingredients.

Visit the recipe card below for a full list of ingredients and instructions!

How to make old fashioned zucchini casserole

Start by chopping the zucchini into half-inch pieces.

chopped zucchini and a knife on a wooden cutting board.

You’ll need 6–7 cups total. It’ll be fine if you’re a little over or under.

Next, place the zucchini, onion, Bisquick, ¾ cup cheddar, salt, and oregano in a large bowl. (You’ll save the remaining ¾ cup of cheese for the top.)

bowl of chopped zucchini and shredded cheddar coated in bisquick.

Then, whisk together the eggs and oil.

egg mixture in a white bowl with a whisk.

Pour the egg mixture over the zucchini mixture, and toss gently to combine.

Pour the mixture into a greased 8×8 inch pan, and top with the remaining ¾ cup cheese.

casserole dish filled with raw zucchini and topped with shredded cheddar.

Bake the zucchini casserole for 45–50 minutes, or until the casserole no longer jiggles in the middle when you jostle the pan back and forth.

Let the casserole cool for 10 minutes before serving.

Make ahead & Freezing instructions

This old fashioned Zucchini Casserole is best served right after it’s baked. And, I recommend assembling it and then baking it right away.

That said, you can chop the zucchini and onion ahead of time. Cover and store in the refrigerator for up to 24 hours.

Then, when it’s time to make the casserole, you just need to stir everything together and bake it.

zucchini casserole topped with cheese in a gray square casserole dish.

To freeze, bake the casserole as directed and let cool completely. Wrap the pan in plastic wrap and then aluminum foil, and freeze for up to 2 months. Defrost in the refrigerator for 24 hours, then remove the plastic wrap and foil, and bake at 350°F until warm.

Variations

Here are a few ideas for substitutions and variations:

  • Substitute yellow squash for the zucchini (or use a mix of the two)
  • Use dried basil instead of dried oregano
  • Use fresh oregano or fresh basil instead of dried oregano (triple the amount)
  • Use colby jack or your favorite type of shredded cheese in place of the cheddar
slice of zucchini casserole on a gray plate.

What to serve with zucchini casserole

I love serving this casserole on a warm summer evening with grilled chicken or burgers. It’s also really nice with a roast chicken.

Here are few more main dishes to serve it with:

📖 Recipe

slice of old fashioned zucchini casserole on a gray plate.

Old Fashioned Zucchini Casserole

Published by Kate
This easy recipe features chopped zucchini, onion, and oregano in a cheesy, biscuit-like coating.
4.75 from 4 votes
Prep Time 10 minutes
Cook Time 45 minutes
Total Time 55 minutes
Course Side Dish
Cuisine American
Servings 8 servings
Calories 335 kcal

Ingredients
  

  • 6–7 cups chopped zucchini cut into ½ inch cubes (about 4 small zucchini or 2–3 medium)
  • 1 small onion chopped
  • cups Bisquick
  • cups shredded cheddar, divided
  • 1 teaspoon salt
  • 1 teaspoon dried oregano
  • 3 eggs
  • ½ cup vegetable oil

Instructions
 

  • Grease a 9×9 inch dish with cooking spray. Preheat oven to 350°F.
  • Place the zucchini, onion, Bisquick, ¾ cup cheddar, salt, and oregano in a large bowl.
  • In another bowl, whisk together the eggs and vegetable oil. Pour over the zucchini mixture and stir to combine.
  • Pour the mixture into the greased dish and top with the remaining 1 cup cheddar.
  • Bake for 45–50 minutes, or until the casserole no longer jiggles in the middle when you jostle it back and forth. Serve immediately.

Video

Notes

Reheat any leftovers in the microwave or in the oven.
You can substitute yellow squash for the zucchini, if you’d like. You can also use fresh oregano and/or dried or fresh basil in place of the dried oregano. If you’re using fresh herbs, triple the amount. 
To make it ahead, chop the zucchini and onion up to 24 hours in advance, and refrigerate. When you’re ready to bake it, just stir everything together and bake. 
You can freeze the casserole after it’s been baked. Let it cool completely and cover with plastic wrap and then aluminum foil. Freeze for up to 2 months. Defrost for 24 hours in the refrigerator, uncover, and reheat in the oven until warm. 

Nutrition

Calories: 335kcalCarbohydrates: 17gProtein: 10gFat: 26gSaturated Fat: 8gPolyunsaturated Fat: 9gMonounsaturated Fat: 7gTrans Fat: 0.1gCholesterol: 83mgSodium: 701mgPotassium: 376mgFiber: 2gSugar: 6gVitamin A: 524IUVitamin C: 21mgCalcium: 217mgIron: 1mg
Keyword zucchini casserole
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4.75 from 4 votes (4 ratings without comment)

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