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–+ servings
A slice of cheesy zucchini casserole on a spatula.

Cheesy Zucchini Casserole Recipe

Creamy, savory and packed with flavor, this cheesy zucchini casserole will quickly become your favorite way to put garden zucchini to work.
5 from 1 vote
Prep Time 20 minutes
Cook Time 45 minutes
Total Time 1 hour 5 minutes
Servings 6 servings

Ingredients  

  • 1 Tablespoon unsalted butter, plus more for greasing baking dish  
  • 6 medium zucchini
  • 1/2 cup sour cream
  • 1/2 cup mayonnaise
  • 2 teaspoons garlic powder 
  • 2 teaspoons onion powder 
  • 1/2 teaspoon baking powder 
  • 3 large eggs
  • 1 1/2 cups freshly grated sharp cheddar cheese, divided  
  • 1/4 cup grated Parmesan cheese 
  • 1/2 cup crushed Ritz or cheddar cheese crackers 

Instructions 

  • Preheat the oven to 375°F. Grease a 9x13-inch baking dish with butter.
  • Trim the ends of the zucchini then grate them on the large hole of a box grater. Transfer the grated zucchini to a sieve then sprinkle it with 1 teaspoon kosher salt. Let the zucchini sit for 10 minutes.
  • Transfer the zucchini to a kitchen towel and squeeze out as much excess liquid as possible. (Alternately, use your hands to squeeze out the zucchini.) Set it aside. 
  • In a large bowl, whisk together the sour cream, mayonnaise, garlic powder, onion powder, baking powder and eggs with 1/4 teaspoon black pepper. Stir in 1 cup of the cheddar cheese, the Parmesan cheese and the zucchini then transfer the mixture into the greased baking dish. 
  • Bake the casserole for 30 minutes. While it bakes, in a small bowl, stir together the melted butter, crushed crackers and remaining 1/2 cup cheddar cheese. 
  • Remove the casserole from the oven and top it with the cracker mixture then return it to the oven until the crackers are toasted, an additional 10 to 15 minutes. Let cool for 10 minutes then slice and serve. 

Notes

  • VERY IMPORTANT NOTE: You must squeeze an astronomical amount of liquid out of the zucchini or your casserole WILL BE WATERY!
  • To store: Leftover zucchini casserole can be stored in an airtight container in the fridge for up to 3 days. Reheat in the oven or toaster oven to help crisp up the topping again—microwaving works too, but you’ll lose that crunchy texture.
  • To freeze: This casserole freezes best before baking. Assemble the casserole in a freezer-safe dish, cover tightly with foil, and freeze for up to 3 months. Thaw overnight in the fridge before baking as directed, adding 5–10 extra minutes to the bake time if needed.
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