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Best Shredded Zucchini Casserole

Delicious Best Shredded Zucchini Casserole recipe with step-by-step instructions.
Print Recipe
Prep Time 25 minutes
Cook Time 55 minutes
Total Time 1 hour 22 minutes
Servings: 10 servings
Calories: 1775
Ingredients Method

Ingredients
  

For the casserole base
  • 9 cups zucchini (shredded and squeezed dry to prevent sogginess)
  • 1 1/2 tsp salt
  • 2 tsp olive oil (I use Bertolli extra virgin)
  • 1 large yellow onion, finely diced
  • 4 garlic cloves, minced
  • 3 eggs (room temperature, about 70°F)
  • 1/3 cup heavy cream
  • 1 1/2 tsp Dijon mustard
  • 1 1/2 cups Panko breadcrumbs
  • 1 1/4 cups freshly grated Parmesan cheese
  • 1/2 tsp dried oregano
  • 1/2 tsp dried basil
  • 1/2 tsp garlic salt
  • 1/2 tsp dried parsley
  • 1/4 tsp smoked paprika
  • 1/2 tsp freshly cracked black pepper
  • 1/4 tsp crushed red pepper flakes
For the topping
  • 1 1/2 cups sharp cheddar cheese, shredded
  • 1/3 cup Panko breadcrumbs
  • 1 1/2 tbsp unsalted butter (melted and cooled)
  • 1 tsp fresh thyme leaves

Method
 

  1. Shred the zucchini and toss it with salt in a colander, then let it sit for 15 minutes—this draws out excess moisture that would otherwise make the casserole watery. While the zucchini drains, heat the olive oil in a skillet over medium heat and sauté the diced onion for 5 minutes until softened and translucent. Add the minced garlic and cook for 2 minutes more until fragrant. Once the zucchini time is up, press it firmly with paper towels or a clean kitchen towel to remove as much moisture as possible.
  2. In a small bowl, whisk together the room-temperature eggs, heavy cream, and Dijon mustard until well combined. This mixture will act as the binder that holds the casserole together. I find that using room-temperature eggs helps them incorporate more smoothly and creates a more uniform texture throughout the dish.
  3. Preheat your oven to 375°F. In a large bowl, combine the pressed zucchini from Step 1, the sautéed onions and garlic from Step 1, the egg mixture from Step 2, the 1 1/4 cups panko breadcrumbs, grated Parmesan cheese, dried oregano, dried basil, garlic salt, dried parsley, smoked paprika, black pepper, and crushed red pepper flakes. Mix everything thoroughly until the ingredients are evenly distributed and the breadcrumbs are fully incorporated.
  4. Transfer the zucchini mixture from Step 3 into a 9x13 inch baking dish (or similar size), spreading it evenly. Top with the shredded sharp cheddar cheese, distributing it uniformly across the surface. Cover the dish with foil and bake at 375°F for 35 minutes until the casserole is set and the cheese begins to melt.
  5. While the casserole bakes, mix the remaining 1/3 cup panko breadcrumbs with the melted and cooled butter and fresh thyme leaves in a small bowl until the breadcrumbs are evenly coated. After the casserole has baked for 35 minutes, remove it from the oven, uncover it, and sprinkle the buttered breadcrumb mixture over the top. Return the casserole to the oven, uncovered, and bake for another 15 minutes until the topping is golden brown and crispy.
  6. For an extra-golden finish, broil the casserole at 425°F for 1-2 minutes, watching carefully to prevent burning. Remove from the oven and let the casserole stand for 5 minutes before serving—this allows the structure to set fully so it will cut into neat portions. I like to let it rest the full time even though it's tempting to dig in right away, as it really makes a difference in how cleanly it slices.